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Search: id:A139461
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| A139461 |
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a(n) = such k that 2*prime(k+2)+product k successive odd primes is prime = such k that primorial(k+1)/2+2*prime(k+2) is prime. |
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+0
4
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| 1, 2, 3, 4, 8, 9, 11, 12, 27, 28, 37, 47, 64, 321, 415
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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When 1 occured in this sequence see A139461
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MATHEMATICA
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k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k + 2*Prime[n + 1]], AppendTo[a, n - 1]], {n, 2, 2000}]; a (*Artur Jasinski*)
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CROSSREFS
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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: A045577 A111020 A002971 this_sequence A126421 A116111 A032859
Adjacent sequences: A139458 A139459 A139460 this_sequence A139462 A139463 A139464
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Apr 22 2008
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