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

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

Offset

1,3

Comments

The next term has 154 decimal digits.

Links

Table of n, a(n) for n=1..8.

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).

Prog

(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 */

Crossrefs

Row sums of A095422, A095421.

Sequence in context: A275453 A268552 A227493 * A174766 A265191 A184895

Adjacent sequences: A095420 A095421 A095422 * A095424 A095425 A095426

Keyword

easy,nonn

Author

Goran Kilibarda, Vladeta Jovovic, Jun 04 2004

Status

approved