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A291316
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Expansion of x/(1-x) + x^4*(1-x)/(1-x^3) + x^7*(1-x)*(1-x^3)/(1-x^5) + ... in powers of x.
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0
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1, 1, 1, 2, 0, 1, 3, -1, 1, 2, 0, 2, 1, 0, -1, 4, 2, -1, 2, -3, 4, 3, -1, 2, 0, 1, 1, 2, -2, 2, 5, 2, -3, 0, 1, -1, 6, 0, 4, -2, -1, 3, -1, 2, 0, 4, -2, 2, 4, -2, 1, 5, -2, -2, -2, 3, 6, 1, 3, -2, 4, -3, -1, -2, 3, 6, 2, 0, -4, 5, 1, 3, -1, 0, 0, 4, -1, -2, 4
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OFFSET
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1,4
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LINKS
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FORMULA
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EXAMPLE
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G.f. = x + x^2 + x^3 + 2*x^4 + x^6 + 3*x^7 - x^8 + x^9 + 2*x^10 + ...
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PROG
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(PARI) {a(n) = my(A); if( n<0, 0, A = x * O(x^n); A = sum(k=0, (n-1)\3, x^(3*k+1) * prod(i=1, k, 1 - x^(2*i-1), 1 + A) / (1 - x^(2*k+1)) ); polcoeff(A, n))};
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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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