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Search: id:A118777
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| A118777 |
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a(0) = 1; n > 0: a(n) = a(n-1) + d, d = -/+1 if n is prime/composite. |
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+0
1
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| 1, 2, 1, 0, 1, 0, 1, 0, 1, 2, 3, 2, 3, 2, 3, 4, 5, 4, 5, 4, 5, 6, 7, 6, 7, 8, 9, 10, 11, 10, 11, 10, 11, 12, 13, 14, 15, 14, 15, 16, 17, 16, 17, 16, 17, 18, 19, 18, 19, 20, 21, 22, 23, 22, 23, 24, 25, 26, 27, 26, 27, 26, 27, 28, 29, 30, 31, 30, 31, 32, 33, 32, 33, 32, 33, 34, 35, 36
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n)=n + 1 - 2*primepi(n), n=0,1,2,...
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MATHEMATICA
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(*1*) a=1; s={a}; Do[b=a+If[PrimeQ[n], -1, 1]; AppendTo[s, b]; a=b, {n, 100}]; s
(*2*) Table[n + 1 - 2*PrimePi[n], {n, 0, 100}]
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CROSSREFS
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Sequence in context: A085004 A095774 A071993 this_sequence A073068 A116683 A079748
Adjacent sequences: A118774 A118775 A118776 this_sequence A118778 A118779 A118780
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov, May 22 2006
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