OFFSET
0,5
FORMULA
a(n) = n!*Sum_{k=0..n-1} A009940(k)/(k!*(n-k)).
a(n) = (4*n - 7)*a(n-1) - (6*n^2 - 25*n + 27)*a(n-2) + (n-2)*(4*n^2 - 21*n + 28)*a(n-3) - (n-3)^3*(n-2)*a(n-4). - Vaclav Kotesovec, Mar 12 2024
MATHEMATICA
a[n_]:=n! D[LaguerreL[n, x, 1], x]/.{x->0}; Array[a, 25, 0]
Table[n! Sum[LaguerreL[k, 1]/(n-k), {k, 0, n-1}], {n, 0, 25}]
RecurrenceTable[{(-3 + n)^3*(-2 + n)*a[n-4] - (-2 + n)*(28 - 21*n + 4*n^2)*a[n-3] + (27 - 25*n + 6*n^2)*a[n-2] + (7 - 4*n)*a[n-1] + a[n] == 0, a[0] == 0, a[1] == 1, a[2] == 1, a[3] == -1}, a, {n, 0, 20}] (* Vaclav Kotesovec, Mar 12 2024 *)
PROG
(PARI) a(n) = n!*sum(k=0, n-1, pollaguerre(k, 0, 1)/(n-k)); \\ Michel Marcus, Mar 12 2024
CROSSREFS
KEYWORD
sign
AUTHOR
Rui Xian Siew, Mar 10 2024
STATUS
approved