a(n) = Sum_{k=0..n} (k+1) * A026637(n,k).

Terms

a(0) =1a(1) =3a(2) =8a(3) =25a(4) =60a(5) =147a(6) =336a(7) =765a(8) =1700a(9) =3751a(10) =8184a(11) =17745a(12) =38220a(13) =81915a(14) =174752a(15) =371365a(16) =786420a(17) =1660239a(18) =3495240a(19) =7340025a(20) =15379100a(21) =32156323a(22) =67108848a(23) =139810125a(24) =290805060a(25) =603979767a(26) =1252698776a(27) =2594876065a(28) =5368709100