a(n) = Sum_{k=0..n} (k+1) * A026626(n,k).

Terms

a(0) =1a(1) =3a(2) =10a(3) =25a(4) =66a(5) =154a(6) =360a(7) =810a(8) =1810a(9) =3982a(10) =8700a(11) =18850a(12) =40614a(13) =87030a(14) =185680a(15) =394570a(16) =835578a(17) =1763998a(18) =3713700a(19) =7798770a(20) =16340302a(21) =34166086a(22) =71303160a(23) =148548250a(24) =308980386a(25) =641728494a(26) =1330992460a(27) =2757055810a(28) =5704253430