a(n) = (-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120.

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =10a(5) =20a(6) =21a(7) =-27a(8) =-201a(9) =-626a(10) =-1486a(11) =-3035a(12) =-5608a(13) =-9632a(14) =-15637a(15) =-24267a(16) =-36291a(17) =-52614a(18) =-74288a(19) =-102523a(20) =-138698a(21) =-184372a(22) =-241295a(23) =-311419a(24) =-396909a(25) =-500154a(26) =-623778a(27) =-770651a(28) =-943900a(29) =-1146920