login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A346751
Expansion of e.g.f. log( 1 + x^3 * exp(x) / 3! ).
4
0, 0, 0, 1, 4, 10, 10, -105, -1064, -6076, -16680, 129525, 2642860, 25431406, 130210444, -639438345, -26431524560, -382074099000, -3083015556624, 5641134587049, 726952330301940, 14940678486798610, 173111303303845060, 258953439321230731, -43858702741534022936
OFFSET
0,5
LINKS
FORMULA
a(0) = 0; a(n) = binomial(n,3) - (1/n) * Sum_{k=1..n-1} binomial(n,k) * binomial(n-k,3) * k * a(k).
a(n) = n! * Sum_{k=1..floor(n/3)} (-1)^(k-1) * k^(n-3*k-1)/(6^k * (n-3*k)!). - Seiichi Manyama, Dec 14 2023
MATHEMATICA
nmax = 24; CoefficientList[Series[Log[1 + x^3 Exp[x]/3!], {x, 0, nmax}], x] Range[0, nmax]!
a[0] = 0; a[n_] := a[n] = Binomial[n, 3] - (1/n) Sum[Binomial[n, k] Binomial[n - k, 3] k a[k], {k, 1, n - 1}]; Table[a[n], {n, 0, 24}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Aug 01 2021
STATUS
approved