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#20 by N. J. A. Sloane at Mon Aug 19 16:50:34 EDT 2019
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#19 by Andrew Howroyd at Mon Aug 19 16:33:41 EDT 2019
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#18 by Andrew Howroyd at Mon Aug 19 16:33:31 EDT 2019
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| FORMULA
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E.g.f.: (1 - x)/(x + 3 - 2*exp(x)). - Andrew Howroyd, Aug 19 2019
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(PARI) seq(n)={Vec(-1+serlaplace((1-x)/(x+3-2*exp(x))) + O(x*x^n), -n)} \\ Andrew Howroyd, Aug 19 2019
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proposed
editing
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#17 by Michael De Vlieger at Mon Aug 19 16:22:12 EDT 2019
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#16 by Michael De Vlieger at Mon Aug 19 16:22:06 EDT 2019
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| LINKS
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Michael De Vlieger, <a href="/A308352/b308352.txt">Table of n, a(n) for n = 1..413</a>
Jimmy Devillet, Miguel Couceiro, <a href="http://orbilu.uni.lu/handle/10993/39720">Characterizations and enumerations of classes of quasitrivial n-ary semigroups</a>, 98th Workshop on General Algebra (AAA98, Dresden, Germany 2019).
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approved
editing
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#15 by Vaclav Kotesovec at Wed Jun 05 08:03:11 EDT 2019
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#14 by Vaclav Kotesovec at Wed Jun 05 08:03:07 EDT 2019
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a(n) ~ n! * (4-r) / ((r-1) * (r-3)^(n+1)), where r = -LambertW(-1, -2*exp(-3)). - Vaclav Kotesovec, Jun 05 2019
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approved
editing
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#13 by Vaclav Kotesovec at Wed Jun 05 05:07:59 EDT 2019
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#12 by Vaclav Kotesovec at Wed Jun 05 05:07:53 EDT 2019
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nmax = 20; Rest[CoefficientList[Series[(1 - x)/(3 - 2*E^x + x), {x, 0, nmax}], x] * Range[0, nmax]!] (* Vaclav Kotesovec, Jun 05 2019 *)
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approved
editing
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#11 by Bruno Berselli at Wed May 22 06:27:59 EDT 2019
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