A095423 Number of proper T_0-covers of an n-set.

0, 1, 42, 15654, 1073421588, 4611685989440629944, 85070591730234615704434641716516893512, 28948022309329048855892746252171976959574390130279817915318273546782086570304

Offset: 1

Author

Goran Kilibarda, Vladeta Jovovic, Jun 04 2004

Keywords

• easy
• nonn

Comments

The next term has 154 decimal digits.

Crossrefs

Row sums of A095422, A095421.

Programs

PARI

a(n)=sum(k=0,n, (2*stirling(n+1, k+1, 1) - stirling(n, k,1 )) * 2^(2^k-2) );
vector(10,n,a(n)) /* show terms */

Formula

a(n) = Sum(Stirling1(n, k)*A007537(k), k=1..n).

a(n) = Sum((2*Stirling1(n+1, k+1)-Stirling1(n, k))*2^(2^k-2), k=0..n).