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

A261480

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

Terms

    a(0) =1a(1) =0a(2) =3a(3) =7a(4) =7a(5) =21a(6) =50a(7) =77a(8) =164a(9) =364a(10) =672a(11) =1330a(12) =2787a(13) =5474a(14) =10797a(15) =21945a(16) =43841a(17) =87031a(18) =174812a(19) =350175a(20) =698302a(21) =1397550a(22) =2798250a(23) =5591460a(24) =11181661a(25) =22374660a(26) =44740503a(27) =89467147a(28) =178965787a(29) =357927801

External references