A271790 Number of set partitions of [n] having exactly three pairs (m,m+1) such that m is in some block b and m+1 is in block b+1.

0, 1, 10, 61, 313, 1520, 7373, 36627, 188396, 1007708, 5612677, 32551400, 196447095, 1232448403, 8028591686, 54240974862, 379574487845, 2748022434268, 20558256639096, 158746877185099, 1263892981174760, 10364745848886935, 87464284123646375, 758804198576946316

Offset: 3

Author

Alois P. Heinz, Apr 14 2016

Keywords

• nonn

Examples

			a(4) = 1: 1|2|3|4.
a(5) = 10: 12|3|4|5, 13|24|5, 1|23|4|5, 14|25|3, 1|24|35, 1|2|34|5, 15|2|3|4, 1|25|3|4, 1|2|35|4, 1|2|3|45.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 3..300

Crossrefs

Column k=3 of A185982.