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Search: id:A131694
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| A131694 |
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Numbers n such that S(n) = prime, where S(n) = S(n-1) + A000040(n)*(-1)^n; S(0)=0, n=>1. |
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+0
1
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| 1, 4, 6, 8, 10, 12, 18, 28, 32, 38, 42, 46, 50, 52, 54, 64, 68, 70, 72, 74, 76, 86, 88, 98, 100, 110, 126, 128, 130, 140, 146, 152, 162, 192, 202, 214, 226, 242, 252, 258, 264, 270, 290, 294, 304, 308, 314, 316, 320, 322, 332, 342, 348, 352, 358, 360
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The sequence include as first term the only case for S(n)=negative prime: S(1)=-2.
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EXAMPLE
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S(3)=((0+2*-1)+3*1)+5*-1 = -4, S(4)= -4 + 7*1 = 3 is prime, hence 4 is a term.
S(5)=((((0+2*-1)+3*1)+5*-1)+7*1)+11*-1 = -8, S(6)= -8 + 13*1 = 5 is prime, hence 6 is a term.
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MATHEMATICA
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S=0; Do[S=S+Prime[n]*(-1)^n; If[PrimeQ[S]==True, Print[n]], {n, 1, 10^3, 1}]
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CROSSREFS
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Cf. A008347, A066033, A000040.
Sequence in context: A076298 A034288 A131984 this_sequence A053012 A096160 A073669
Adjacent sequences: A131691 A131692 A131693 this_sequence A131695 A131696 A131697
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KEYWORD
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nonn
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AUTHOR
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Manuel Valdivia (mvaldivia(AT)ugr.es), Oct 03 2007
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