Diagonal sums of number triangle A123490.

Terms

a(0) =1a(1) =2a(2) =5a(3) =10a(4) =22a(5) =48a(6) =112a(7) =274a(8) =715a(9) =1982a(10) =5837a(11) =18180a(12) =59644a(13) =205296a(14) =739032a(15) =2775180a(16) =10846965a(17) =44039754a(18) =185391469a(19) =807776198a(20) =3637193474a(21) =16900721824a(22) =80939650552a(23) =399061251246