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a(n) = n! * [x^n] 1/(1 - Sum_{k=1..n} (exp(k*x) - 1)/k).
2

%I #16 Jul 03 2022 01:54:21

%S 1,1,11,284,13564,1037479,116171621,17916010524,3640962169776,

%T 942959405612913,303168464105203113,118474395231479349050,

%U 55306932183983923942940,30397993745996492901617435,19429788681469866219869997285

%N a(n) = n! * [x^n] 1/(1 - Sum_{k=1..n} (exp(k*x) - 1)/k).

%H Vaclav Kotesovec, <a href="/A355428/b355428.txt">Table of n, a(n) for n = 0..226</a>

%F a(n) ~ c * d^n * n^(2*n + 1/2), where d = 0.4573611067742364103005235654624761643997061199669064548746966610712579358... and c = 2.41592773370058066984975000807924527905758896927935098069320182397... - _Vaclav Kotesovec_, Jul 02 2022

%t Table[n! * SeriesCoefficient[1/(1 + HarmonicNumber[n] + E^((n + 1)*x) * LerchPhi[E^x, 1, n + 1] + Log[1 - E^x]), {x, 0, n}], {n, 0, 20}] (* _Vaclav Kotesovec_, Jul 02 2022 *)

%o (PARI) a(n) = n!*polcoef(1/(1-sum(k=1, n, (exp(k*x+x*O(x^n))-1)/k)), n);

%Y Main diagonal of A355427.

%Y Cf. A319508.

%K nonn

%O 0,3

%A _Seiichi Manyama_, Jul 01 2022