a(n) = Sum_{k=0..n} (k+1) * A026692(n, k).

Terms

a(0) =1a(1) =3a(2) =8a(3) =20a(4) =54a(5) =147a(6) =368a(7) =873a(8) =2150a(9) =5401a(10) =12948a(11) =29952a(12) =71386a(13) =173370a(14) =406720a(15) =928013a(16) =2173248a(17) =5178906a(18) =11994740a(19) =27138972a(20) =62859236a(21) =147973950a(22) =339831168a(23) =764579850a(24) =1757600988a(25) =4102109109a(26) =9364407584a(27) =20984799649