Euler transform of A000056.

Terms

a(0) =1a(1) =1a(2) =7a(3) =31a(4) =100a(5) =364a(6) =1152a(7) =3864a(8) =12102a(9) =37358a(10) =113618a(11) =337562a(12) =990798a(13) =2857926a(14) =8144334a(15) =22902470a(16) =63660695a(17) =175026047a(18) =476242001a(19) =1283435153a(20) =3427047146a(21) =9072455146a(22) =23820491998a(23) =62057045134a(24) =160471504373a(25) =412022656517