Main diagonal of array in A038150.

Terms

a(0) =1a(1) =6a(2) =29a(3) =97a(4) =343a(5) =1131a(6) =3338a(7) =10336a(8) =29644a(9) =88555a(10) =260497a(11) =728358a(12) =2103284a(13) =6020698a(14) =16594432a(15) =46969365a(16) =128670281a(17) =361020986a(18) =1008411198a(19) =2742388946a(20) =7613161908a(21) =20632925370a(22) =56988914979a(23) =156977658446a(24) =423559114311