A274860 Number of set partitions of [n] such that the difference between each element and its index (in the partition) is a multiple of three.

1, 1, 2, 4, 8, 16, 32, 68, 144, 304, 692, 1580, 3602, 8976, 22552, 56850, 157740, 442101, 1249124, 3868420, 12082568, 38117838, 130394944, 448733361, 1559590892, 5817284716, 21787658638, 82365982741, 331668252301, 1339477442569, 5457855667219, 23555837192320

Offset: 0

Author

Alois P. Heinz, Jul 09 2016

Keywords

• nonn

Examples

			a(7) = 68: 1234567, 123456|7, 12345|67, 12345|6|7, 1234|567, 1234|56|7, 1234|5|67, 1234|5|6|7, 123|4567, 123|456|7, 123|45|67, 123|45|6|7, 123|4|567, 123|4|56|7, 123|4|5|67, 123|4|5|6|7, 12|34567, 12|3456|7, 12|345|67, 12|345|6|7, 12|34|567, 12|34|56|7, 12|34|5|67, 12|34|5|6|7, 12|3|4567, 12|3|456|7, 12|3|45|67, 12|3|45|6|7, 12|3|4|567, 12|3|4|56|7, 12|3|4|5|67, 12|3|4|5|6|7, 1567|234, 1|234567, 1|23456|7, 1|2345|67, 1|2345|6|7, 1|234|567, 1|234|56|7, 1|234|5|67, 1|234|5|6|7, 1567|23|4, 1|23|4567, 1|23|456|7, 1|23|45|67, 1|23|45|6|7, 1|23|4|567, 1|23|4|56|7, 1|23|4|5|67, 1|23|4|5|6|7, 1567|2|34, 1|2|34567, 1|2|3456|7, 1|2|345|67, 1|2|345|6|7, 1|2|34|567, 1|2|34|56|7, 1|2|34|5|67, 1|2|34|5|6|7, 1567|2|3|4, 1|2|3|4567, 1|2|3|456|7, 1|2|3|45|67, 1|2|3|45|6|7, 1|2|3|4|567, 1|2|3|4|56|7, 1|2|3|4|5|67, 1|2|3|4|5|6|7.
		

Crossrefs

Column k=3 of A274859.