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Search: id:A035207
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| A035207 |
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Coefficients in expansion of Dirichlet series Product_p (1-(Kronecker(m,p)+1)*p^(-s)+Kronecker(m,p)*p^(-2s))^(-1) for m = 25. |
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+0
2
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| 1, 2, 2, 3, 1, 4, 2, 4, 3, 2, 2, 6, 2, 4, 2, 5, 2, 6, 2, 3, 4, 4, 2, 8, 1, 4, 4, 6, 2, 4, 2, 6, 4, 4, 2, 9, 2, 4, 4, 4, 2, 8, 2, 6, 3, 4, 2, 10, 3, 2, 4, 6, 2, 8, 2, 8, 4, 4, 2, 6, 2, 4, 6, 7, 2, 8, 2, 6, 4, 4, 2, 12, 2, 4, 2, 6, 4, 8, 2, 5, 5, 4, 2, 12, 2, 4, 4, 8, 2, 6, 4, 6, 4, 4, 2, 12, 2, 6, 6, 3, 2, 8, 2
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Number of divisors of n not congruent to 0 mod 5.
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FORMULA
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Multiplicative with a(5^e)=1 and a(p^e)=e+1 for p<>5.
Moebius transform is period 5 sequence [ 1, 1, 1, 1, 0, ...]. - Michael Somos Oct 31 2006
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MAPLE
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for n from 1 to 500 do a := ifactors(n):s := 1:for k from 1 to nops(a[2]) do p := a[2][k][1]:e := a[2][k][2]: if p=5 then b := 1:else b := e+1:fi:s := s*b:od:printf(`%d, `, s); od:
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PROGRAM
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(PARI) {a(n)=if(n<1, 0, sumdiv(n, d, d%5>0))} /* Michael Somos Oct 31 2006 */
(PARI) {a(n)=if(n<1, 0, direuler(p=2, n, 1/(1-X)/if(p==5, 1, 1-X))[n])} /* Michael Somos Oct 31 2006 */
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CROSSREFS
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Cf. A035191.
Sequence in context: A072078 A078378 A141197 this_sequence A071281 A088177 A028507
Adjacent sequences: A035204 A035205 A035206 this_sequence A035208 A035209 A035210
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KEYWORD
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nonn,mult
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Additional comments from Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 26 2001
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