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Search: id:A107742
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| A107742 |
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G.f.: Product(Product(1+x^(i*j),i=1..infinity),j=1..infinity). |
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+0
2
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| 1, 1, 2, 4, 6, 10, 17, 25, 38, 59, 86, 125, 184, 260, 369, 524, 726, 1005, 1391, 1894, 2576, 3493, 4687, 6272, 8373, 11090, 14647, 19294, 25265, 32991, 42974, 55705, 72025, 92895, 119349, 152965, 195592, 249280, 316991, 402215, 508932, 642598
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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N. J. A. Sloane, Transforms
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FORMULA
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Euler transform of A001227. Weigh transform of A000005.
G.f. satisfies: log(A(x)) = Sum_{n>=1} A109386(n)/n*x^n, where A109386(n) = Sum_{d|n} d*Sum_{m|d} (m mod 2). - Paul D. Hanna (pauldhanna(AT)juno.com), Jun 26 2005
G.f.: A(x) = exp( Sum_{n>=1} sigma(n)*x^n/(1-x^(2n)) /n ). [From Paul D. Hanna (pauldhanna(AT)juno.com), Mar 28 2009]
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PROGRAM
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(PARI) a(n)=polcoeff(prod(k=1, n, prod(j=1, n\k, 1+x^(j*k)+x*O(x^n))), n) (Hanna)
(PARI) 1/prod(j=0, N, eta(x^(2*j+1))); Vec(%) - Joerg Arndt (arndt(AT)jjj.de), May 03 2008
(PARI) prod(j=1, N, (1+x^j)^numdiv(j)); Vec(%) - Joerg Arndt (arndt(AT)jjj.de), May 03 2008
(PARI) {a(n)=if(n==0, 1, polcoeff(exp(sum(m=1, n, sigma(m)*x^m/(1-x^(2*m)+x*O(x^n))/m)), n))} [From Paul D. Hanna (pauldhanna(AT)juno.com), Mar 28 2009]
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CROSSREFS
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Cf. A006171, A109386.
Sequence in context: A048833 A070689 A091611 this_sequence A158510 A004695 A014216
Adjacent sequences: A107739 A107740 A107741 this_sequence A107743 A107744 A107745
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 11 2005
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EXTENSIONS
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More terms from Paul D. Hanna (pauldhanna(AT)juno.com), Jun 26 2005
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