Row sums of A321623.

Terms

a(0) =1a(1) =4a(2) =20a(3) =108a(4) =604a(5) =3444a(6) =19876a(7) =115644a(8) =676748a(9) =3977316a(10) =23451700a(11) =138634764a(12) =821221692a(13) =4872734676a(14) =28952250564a(15) =172222729308