a(n) = s(n,n) + s(n,n-1) + s(n,n-2), where s(n,k) are the unsigned Stirling numbers of the first kind (see A132393).

A308305

a(n) = s(n,n) + s(n,n-1) + s(n,n-2), where s(n,k) are the unsigned Stirling numbers of the first kind (see A132393).

Terms

    a(0) =1a(1) =2a(2) =6a(3) =18a(4) =46a(5) =101a(6) =197a(7) =351a(8) =583a(9) =916a(10) =1376a(11) =1992a(12) =2796a(13) =3823a(14) =5111a(15) =6701a(16) =8637a(17) =10966a(18) =13738a(19) =17006a(20) =20826a(21) =25257a(22) =30361a(23) =36203a(24) =42851a(25) =50376a(26) =58852a(27) =68356a(28) =78968a(29) =90771

External references