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A139460
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a(n) = m such that 2*prime(n+m+1) + (product of n successive odd primes) is prime.
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4
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1, 1, 1, 1, 2, 3, 3, 1, 1, 2, 1, 1, 9, 2, 7, 21, 7, 25, 4, 3, 18, 7, 4, 7, 11, 5, 1, 1, 61, 5, 20, 6, 22, 16, 11, 17, 1, 70, 6, 5, 5, 22, 9, 52, 108, 16, 1, 32, 42, 15, 5, 66, 6, 8, 3, 38, 17, 4, 23, 93, 8, 16, 6, 1, 39, 7, 9, 10, 21, 57, 40, 2, 15, 39, 16, 7, 5, 13, 138, 95, 58, 8, 47, 11, 39
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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COMMENTS
| Or, a(n) = m such that primorial(n+1)/2+2*prime(n+m+1) is prime.
For positions of 1's in this sequence see A139461
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MATHEMATICA
| k = 1; a = {}; Do[k = k*Prime[n]; m = 1; While[ ! PrimeQ[k + 2*Prime[n + m]], m++ ]; Print[m]; AppendTo[a, m], {n, 2, 200}]; a (*Artur Jasinski*)
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CROSSREFS
| Cf. A067026, A067027, A139439, A139440, A139441, A139442, A139443, A139444, A139445, A139446, A139447, A139448, A139449, A139450, A139451, A139452, A139453, A139454, A139455, A139456, A139457, A103514, A139460, A139461, A139462, A139463.
Sequence in context: A124798 A171872 A005135 * A105244 A145854 A097663
Adjacent sequences: A139457 A139458 A139459 * A139461 A139462 A139463
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Apr 22 2008; definition corrected May 09 2008
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