Diagonal sums of A103209, viewed as number triangle.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =8a(5) =26a(6) =107a(7) =492a(8) =2481a(9) =13599a(10) =81288a(11) =531343a(12) =3790344a(13) =29279668a(14) =242278645a(15) =2125160800a(16) =19608039385a(17) =189437263949