3-Bell numbers: E.g.f.: exp(3*z + exp(z) - 1).

Terms

a(0) =1a(1) =4a(2) =17a(3) =77a(4) =372a(5) =1915a(6) =10481a(7) =60814a(8) =372939a(9) =2409837a(10) =16360786a(11) =116393205a(12) =865549453a(13) =6713065156a(14) =54190360453a(15) =454442481041