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

0,3

Links

Table of n, a(n) for n=0..31.

Example

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.

Sequence in context: A336010 A180208 A100139 * A076766 A344492 A359389

Adjacent sequences: A274857 A274858 A274859 * A274861 A274862 A274863

Keyword

nonn

Author

Alois P. Heinz, Jul 09 2016

Status

approved