A308296 a(n) = (1/n!) * Sum_{i_1=1..n} Sum_{i_2=1..n} ... Sum_{i_n=1..n} multinomial(i_1+i_2+...+i_n; i_1, i_2, ... , i_n).

1, 1, 7, 842, 7958726, 15467641899285, 10893033763705794846727, 4247805448772073978048752721163278, 1299618941291522676629215597535104557826094801396, 419715170056359079715862408734598208208707081189266290220651371206

Offset: 0

Author

Seiichi Manyama, May 19 2019

Keywords

• nonn

Examples

			a(2) = (1/2) * (binomial(1+1,1) + binomial(1+2,2) + binomial(2+1,1) + binomial(2+2,2)) = 7.
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..27

Crossrefs

Cf. A144510, A144512, A274762, A281901.

Programs

PARI

{a(n) = sum(i=n, n^2, i!*polcoef(sum(j=1, n, x^j/j!)^n, i))/n!}

Formula

a(n) = A144510(n,n).