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A202150
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a(n) = A202146( 3*n*(n+1) ) for n>=0.
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2
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1, 1, 1, -1, 1, -1, 1, 3, 1, -1, 1, -1, 1, 1, 1, -1, -1, 1, 1, 1, 1, -1, 3, -1, 1, 1, 1, 1, -1, -1, 1, 1, 3, -1, -1, -1, 1, 3, 3, -1, 1, -1, 1, 1, 1, 1, -1, -1, 1, 1, 1, -1, 1, -1, 1, 1, 1, -1, 3, 1, 1, 1, 1, -1, -1, -1, 3, 3, 1, -1, -1, 1, 1, -1, 1, -1, 3
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OFFSET
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0,8
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COMMENTS
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Conjecture: this sequence consists of all odd terms in A202146; the g.f. of A202146 is 1/(1-x) + Sum_{n>=1} x^n/(1-x) * Product_{k=1..n} (1 - x^k) / (1 - x^(2*k+1)), which by the conjecture has an odd coefficient of x^m iff m = 3*n*(n+1) for n>=0. The conjecture holds for at least the initial 30300 terms of A202146.
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LINKS
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PROG
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(PARI) {a(n)=polcoeff((1+sum(m=1, 3*n*(n+1), x^m*prod(k=1, m, (1-x^k)/(1-x^(2*k+1) +x*O(x^(3*n*(n+1)))))))/(1-x+x*O(x^(3*n*(n+1)))), 3*n*(n+1))}
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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