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A206139
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G.f.: A(x) = Sum_{n>=0} x^(n*(n+1)/2) / Product_{k=1..n} (1-x^k)^(n-k+1).
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2
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1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 88, 141, 224, 356, 563, 890, 1401, 2202, 3448, 5386, 8386, 13025, 20175, 31180, 48077, 73976, 113588, 174057, 266174, 406224, 618729, 940552, 1427038, 2161122, 3266956, 4930052, 7427314, 11171332, 16776169, 25154204
(list;
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listen;
history;
text;
internal format)
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OFFSET
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0,4
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LINKS
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Vaclav Kotesovec, Table of n, a(n) for n = 0..400
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EXAMPLE
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G.f.: A(x) = 1 + x + x^2 + 2*x^3 + 3*x^4 + 5*x^5 + 8*x^6 + 13*x^7 +...
where
A(x) = 1 + x/(1-x) + x^3/((1-x)^2*(1-x^2)) + x^6/((1-x)^3*(1-x^2)^2*(1-x^3)) + x^10/((1-x)^4*(1-x^2)^3*(1-x^3)^2*(1-x^4)) +...
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PROG
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(PARI) {a(n)=polcoeff(sum(m=0, n, x^(m*(m+1)/2)/prod(k=1, m, (1-x^k +x*O(x^n))^(m-k+1))), n)}
for(n=0, 61, print1(a(n), ", "))
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CROSSREFS
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Cf. A206119.
Sequence in context: A261606 A261598 A261587 * A023440 A225396 A290689
Adjacent sequences: A206136 A206137 A206138 * A206140 A206141 A206142
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna, Feb 04 2012
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STATUS
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approved
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