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A074745
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a(n) = sum_{k=1..n} prime(k)*prime(k+1).
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4
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6, 21, 56, 133, 276, 497, 820, 1257, 1924, 2823, 3970, 5487, 7250, 9271, 11762, 14889, 18488, 22575, 27332, 32515, 38282, 44839, 52226, 60859, 70656, 81059, 92080, 103743, 116060, 130411, 147048, 164995, 184038, 204749, 227248, 250955
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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) = Sum_{k=1..n} prime(k)*prime(k+1) = Sum_{k=1..n} A006094(k).
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MAPLE
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with(numtheory): a := proc(n) local k: RETURN(add(ithprime(k)*ithprime(k+1), k=1..n)):end;
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MATHEMATICA
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PROG
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(PARI) a(n) = sum(k=1, n, prime(k)*prime(k+1)); \\ Michel Marcus, Jan 16 2015
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Sep 06 2002
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STATUS
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approved
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