Search: a089536 -id:a089536
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A085745
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Numbers m such that 2^m + m is a semiprime.
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+10
4
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2, 11, 23, 34, 59, 69, 87, 95, 119, 123, 129, 171, 197, 239, 341, 425, 455, 471, 515, 519, 635, 765, 959, 1115, 1181, 1210
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = 2*k <=> A089535(n) is even <=> A089536(n) = 2 <=> A089537(n) = 4^k/2 + k, and for any prime of this form, there is a term a(n) = 2*k in this sequence. - M. F. Hasler, Oct 08 2009
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MATHEMATICA
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Select[Range[1300], PrimeOmega[2^#+#]==2&] (* Harvey P. Dale, Dec 18 2014 *)
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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A089535
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Semiprimes of the form 2^k + k.
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+10
3
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6, 2059, 8388631, 17179869218, 576460752303423547, 590295810358705651781, 154742504910672534362390615, 39614081257132168796771975263, 664613997892457936451903530140172407, 10633823966279326983230456482242756731, 680564733841876926926749214863536423041
(list;
graph;
refs;
listen;
history;
text;
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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Select[Table[2^k+k, {k, 200}], PrimeOmega[#]==2&] (* Harvey P. Dale, Aug 11 2024 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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3, 71, 270601, 8589934609, 82351536043346221, 84327972908386521683, 30948500982134506872478123, 33335112753917098113257, 508503441386731397438334759097301, 64111463765644650653, 18841609804988852361375097, 306274945731599108294378939441, 22457217721139859611914512110646173819
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Offset changed to 1 and more terms from Jinyuan Wang, Jul 30 2021
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STATUS
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approved
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