Set partitions without singletons: number of partitions of an n-set into blocks of size > 1. Also number of cyclically spaced (or feasible) partitions.

A000296

Set partitions without singletons: number of partitions of an n-set into blocks of size > 1. Also number of cyclically spaced (or feasible) partitions.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =1a(4) =4a(5) =11a(6) =41a(7) =162a(8) =715a(9) =3425a(10) =17722a(11) =98253a(12) =580317a(13) =3633280a(14) =24011157a(15) =166888165a(16) =1216070380a(17) =9264071767a(18) =73600798037a(19) =608476008122

External references