a(n) = Sum_{k=0..n} (k+1) * A026703(n, k).

Terms

a(0) =1a(1) =3a(2) =10a(3) =30a(4) =81a(5) =224a(6) =564a(7) =1485a(8) =3605a(9) =9207a(10) =21846a(11) =54665a(12) =127687a(13) =314895a(14) =727176a(15) =1774018a(16) =4061295a(17) =9825774a(18) =22342050a(19) =53699310a(20) =121438581a(21) =290333324a(22) =653649804a(23) =1555933100a(24) =3489984875a(25) =8277300090a(26) =18507864886a(27) =43760782384a(28) =97585469205