A099950 Number of 2-sparse nonoverlapping partitions of n.

1, 1, 1, 2, 4, 10, 27, 80, 255, 870, 3155, 12100, 48871, 207162, 918944, 4254690, 20513838, 102784942, 534205629, 2875098840, 15999114433, 91923562922, 544606671776, 3323112062994, 20860869818386, 134585869671342

Offset

0,4

Links

Table of n, a(n) for n=0..25.

V. E. Adler, Set partitions and integrable hierarchies, arXiv:1510.02900 [nlin.SI], 2015.

M. Klazar, Bell numbers, their relatives and algebraic differential equations

M. Klazar, Bell numbers, their relatives and algebraic differential equations, J. Combin. Theory, A 102 (2003), 63-87.

Prog

(PARI) {a(n)=local(A); if(n<0, 0, A=O(x^0); for(i=0, n\2, A=(1+x)/(1-x^2*subst(A, x, x/(1-x)))); polcoeff(A, n))} /* Michael Somos, Sep 22 2005 */

Crossrefs

Sequence in context: A148106 A291210 A340635 * A121690 A138356 A287693

Adjacent sequences: A099947 A099948 A099949 * A099951 A099952 A099953

Keyword

nonn,easy

Author

N. J. A. Sloane, Nov 12 2004

Status

approved