a(n) = Sum_{k=0..n} (k+1) * A026659(n,k).

Terms

a(0) =1a(1) =3a(2) =8a(3) =25a(4) =60a(5) =147a(6) =336a(7) =882a(8) =1960a(9) =4631a(10) =10104a(11) =25207a(12) =54292a(13) =125895a(14) =268576a(15) =653191a(16) =1383228a(17) =3172981a(18) =6679960a(19) =15996204a(20) =33515856a(21) =76350225a(22) =159339600a(23) =377580850a(24) =785368168a(25) =1780545051a(26) =3692982328a(27) =8684805392a(28) =17968562880