a(n) = floor((n+2)^(n+2)/n^n).

Terms

a(0) =4a(1) =27a(2) =64a(3) =115a(4) =182a(5) =263a(6) =359a(7) =470a(8) =596a(9) =736a(10) =891a(11) =1061a(12) =1246a(13) =1445a(14) =1660a(15) =1889a(16) =2132a(17) =2391a(18) =2664a(19) =2953a(20) =3256a(21) =3573a(22) =3906a(23) =4253a(24) =4615a(25) =4992a(26) =5384a(27) =5790a(28) =6211a(29) =6647