Second elementary symmetric function of 3,4,...,n+3.

Terms

a(0) =12a(1) =47a(2) =119a(3) =245a(4) =445a(5) =742a(6) =1162a(7) =1734a(8) =2490a(9) =3465a(10) =4697a(11) =6227a(12) =8099a(13) =10360a(14) =13060a(15) =16252a(16) =19992a(17) =24339a(18) =29355a(19) =35105a(20) =41657a(21) =49082a(22) =57454a(23) =66850a(24) =77350a(25) =89037a(26) =101997a(27) =116319a(28) =132095a(29) =149420