a(n) = Sum_{k=0..n} (k+1) * T(n,k), with T given by A026374.

Terms

a(0) =1a(1) =3a(2) =10a(3) =25a(4) =75a(5) =175a(6) =500a(7) =1125a(8) =3125a(9) =6875a(10) =18750a(11) =40625a(12) =109375a(13) =234375a(14) =625000a(15) =1328125a(16) =3515625a(17) =7421875a(18) =19531250a(19) =41015625a(20) =107421875a(21) =224609375a(22) =585937500a(23) =1220703125a(24) =3173828125a(25) =6591796875a(26) =17089843750a(27) =35400390625a(28) =91552734375a(29) =189208984375