A261479 Number of set partitions of [2n] into exactly n parts such that no part contains two elements with a circular distance less than three.

1, 0, 0, 1, 7, 458, 18944, 858023, 42615547, 2331292564, 140077132527, 9199520194445, 656844469384222, 50720708063406821, 4215138323234299756, 375319710150454887887, 35660986210126871452435, 3602425696957042245685448, 385625195068544676072425069

Offset

0,5

Comments

The circular distance of 1 and n is 1 (for n>1).

Links

Alois P. Heinz, Table of n, a(n) for n = 0..50

Formula

a(n) = A261477(2n,n).

Example

a(0) = 1: {}.
a(3) = 1: 14|25|36.
a(4) = 7: 14|26|37|58, 14|27|36|58, 15|26|37|48, 15|26|38|47, 15|27|36|48, 16|25|37|48, 16|25|38|47.
a(5) = 458: 147|258|3,10|6|9, 147|258|36|9|10, 147|258|39|6|10, ..., 1|29|36,10|47|58, 1|29|36|47,10|58, 1|2|369|47,10|58.

Crossrefs

Cf. A261477.

Sequence in context: A009660 A024097 A203060 * A241363 A196540 A215890

Adjacent sequences: A261476 A261477 A261478 * A261480 A261481 A261482

Keyword

nonn

Author

Alois P. Heinz, Aug 20 2015

Status

approved