OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..214
FORMULA
a(n) = n! * A096131(n) = n! * Sum_{k=1..n} binomial(k*n, n).
EXAMPLE
a(2) = 1*2 + 3*4 = 14.
a(3) = 1*2*3 + 4*5*6 + 7*8*9 = 630.
a(4) = 1*2*3*4 + 5*6*7*8 + 9*10*11*12 + 13*14*15*16 = 57264.
MATHEMATICA
a[n_] := n! * Sum[Binomial[k*n, n], {k, 1, n}]; Array[a, 15] (* Amiram Eldar, May 01 2021 *)
PROG
(PARI) {a(n) = sum(i=1, n, prod(j=(i-1)*n+1, i*n, j))}
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jul 23 2020
STATUS
approved