OFFSET
0,3
COMMENTS
Let A = the sum of the n-th powers of the first 2^{n-1} terms of A001969, and similarly let B = the sum of the n-th powers of the first 2^{n-1} terms of A000069. Then a(n) = |A-B|. - Jeffrey Shallit, Nov 29 2019
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..77
Richard P. Stanley, Acyclic Orientations of Graphs, Discrete Mathematics, 5 (1973), pages 171-178, doi:10.1016/0012-365X(73)90108-8.
FORMULA
From Mehdi Naima, Mar 09 2022: (Start)
a(n) = a(n-1)*n*2^(n-1), a(0) = 1.
G.f. satisfies A(x) = 1 + x * (x * A(2*x))'. (End)
MAPLE
a:= n-> 2^(n*(n-1)/2)*n!:
seq(a(n), n=0..15); # Alois P. Heinz, Apr 21 2020
MATHEMATICA
Table[2^((n(n-1))/2) n!, {n, 0, 20}] (* Harvey P. Dale, Dec 16 2012 *)
PROG
(PARI) a(n) = n! << binomial(n, 2); \\ Kevin Ryde, Mar 10 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved