Expansion of e.g.f. (1 + x * (exp(x) - 1))^2.

Terms

a(0) =1a(1) =0a(2) =4a(3) =6a(4) =32a(5) =130a(6) =432a(7) =1274a(8) =3488a(9) =9090a(10) =22880a(11) =56122a(12) =134928a(13) =319202a(14) =745136a(15) =1719930a(16) =3931712a(17) =8912386a(18) =20053440a(19) =44825978a(20) =99614000a(21) =220200162a(22) =484441232a(23) =1061157946a(24) =2315254752a(25) =5033163650a(26) =10905189152a(27) =23555209914a(28) =50734299728a(29) =108984793570