OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..386
FORMULA
a(n) ~ (-1)^n * n^n * (1 + 1/n^2 - 1/n^3 + 2/n^4 - 2/n^5 + 4/n^6 - 4/n^7 + 7/n^8 - 8/n^9 + 12/n^10), for coefficients see A002865. - Vaclav Kotesovec, Sep 19 2017
MAPLE
b:= proc(n, i, k) option remember; `if`(n=0 or i=1, (-k)^n,
`if`(i>n, 0, b(n-i, i, k))+b(n, i-1, k))
end:
a:= n-> b(n$3):
seq(a(n), n=0..23);
MATHEMATICA
b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i == 1, (-k)^n, If[i > n, 0, b[n - i, i, k]] + b[n, i - 1, k]];
a[n_] := If[n == 0, 1, b[n, n, n]];
a /@ Range[0, 23] (* Jean-François Alcover, Dec 30 2020, after Alois P. Heinz *)
CROSSREFS
KEYWORD
sign
AUTHOR
Alois P. Heinz, Sep 19 2017
STATUS
approved