A354685 a(n) = n! * Sum_{k=1..n} (-1)^(n-k) * Stirling1(n,k) * H(k), where H(k) is the k-th harmonic number.

0, 1, 5, 50, 854, 22354, 833244, 41974176, 2748169584, 226916044848, 23069499189120, 2831994888419520, 413051278946186880, 70608112721914654080, 13982696139441640584960, 3175762393024883382067200, 820007850688478572529203200, 238863690100874514528150681600

Offset

0,3

Links

Vaclav Kotesovec, Table of n, a(n) for n = 0..250

Vaclav Kotesovec, Graph - the asymptotic ratio

Formula

Sum_{n>=0} a(n) * x^n / n!^2 = Sum_{n>=1} H(n) * (-log(1-x))^n / n!.

a(n) ~ n!^2 * (log(log(n)) + gamma + 1/log(n)), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Jun 03 2022

Mathematica

Table[n! Sum[(-1)^(n - k) StirlingS1[n, k] HarmonicNumber[k], {k, 1, n}], {n, 0, 17}]
nmax = 17; CoefficientList[Series[Sum[HarmonicNumber[k] (-Log[1 - x])^k/k!, {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!^2

Crossrefs

Cf. A001008, A002805, A087751, A222059, A302548, A354686.

Sequence in context: A320502 A116906 A051893 * A247951 A082100 A299353

Adjacent sequences: A354682 A354683 A354684 * A354686 A354687 A354688

Keyword

nonn

Author

Ilya Gutkovskiy, Jun 03 2022

Status

approved