a(n) = Sum_{k=0..n} (k+1) * A026725(n, k).

Terms

a(0) =1a(1) =3a(2) =8a(3) =22a(4) =53a(5) =136a(6) =312a(7) =768a(8) =1712a(9) =4101a(10) =8971a(11) =21082a(12) =45507a(13) =105435a(14) =225347a(15) =516424a(16) =1095353a(17) =2488480a(18) =5246176a(19) =11834584a(20) =24826412a(21) =55677436a(22) =116321132a(23) =259585768a(24) =540454158a(25) =1201026646a(26) =2493149402a(27) =5520322840a(28) =11430160964