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A185300
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Numbers k such that (sum of the decimal digits of k) + (product of the decimal digits of k) is prime.
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5
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1, 11, 12, 13, 15, 16, 18, 19, 20, 21, 23, 25, 27, 29, 30, 31, 32, 34, 35, 37, 43, 45, 50, 51, 52, 53, 54, 56, 57, 58, 59, 61, 65, 70, 72, 73, 75, 78, 79, 81, 85, 87, 89, 91, 92, 95, 97, 98, 101, 102, 104, 106, 110, 120, 140, 160, 200, 201, 203, 205, 209, 210, 223, 225, 230, 232
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listen;
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internal format)
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OFFSET
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1,2
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LINKS
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EXAMPLE
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236 is in the sequence because 2 + 3 + 6 + 2*3*6 = 11 + 36 = 47 is prime.
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MAPLE
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A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc:
A007954 := proc(n) mul(d, d=convert(n, base, 10)) ; end proc:
for n from 1 to 300 do if isA185300(n) then printf("%a, ", n) ; end if; end do: # R. J. Mathar, Feb 08 2011
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PROG
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(Magma) [n: n in [1..232] | IsPrime(&+Intseq(n)+&*Intseq(n))]; // Bruno Berselli, Aug 02 2012
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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