Diagonal sums of number triangle A122919.

Terms

a(0) =1a(1) =1a(2) =4a(3) =12a(4) =39a(5) =129a(6) =436a(7) =1498a(8) =5218a(9) =18386a(10) =65420a(11) =234734a(12) =848403a(13) =3086001a(14) =11288412a(15) =41499354a(16) =153247278a(17) =568188606a(18) =2114334312a(19) =7893906144a(20) =29561195238a(21) =111007927386a(22) =417918303144