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A292312
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Expansion of Product_{k>=1} (1 - k^k*x^k).
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6
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1, -1, -4, -23, -229, -2761, -42615, -758499, -15702086, -365588036, -9516954786, -273061566624, -8575969258607, -292418459301779, -10762887030763337, -425243370397722674, -17953905924215881215, -806666656048846472309
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) ~ -n^n * (1 - exp(-1)/n - (exp(-1)/2 + 4*exp(-2))/n^2). - Vaclav Kotesovec, Sep 14 2017
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MAPLE
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seq(coeff(series(mul((1-k^k*x^k), k=1..n), x, n+1), x, n), n = 0 .. 20); # Muniru A Asiru, Oct 31 2018
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MATHEMATICA
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terms = 18; CoefficientList[Product[(1 - k^k*x^k), {k, 1, terms}] + O[x]^(terms), x] (* Jean-François Alcover, Nov 11 2017 *)
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PROG
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(PARI) {a(n) = polcoeff(prod(k=1, n, 1-k^k*x^k+x*O(x^n)), n)}
(Magma) m:=20; R<x>:=PowerSeriesRing(Rationals(), m); Coefficients(R! ( (&*[(1 - k^k*x^k): k in [1..m]]) )); // G. C. Greubel, Oct 31 2018
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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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