Diagonal sums of number triangle A114709.

Terms

a(0) =1a(1) =0a(2) =3a(3) =6a(4) =31a(5) =126a(6) =589a(7) =2772a(8) =13485a(9) =66780a(10) =336207a(11) =1714698a(12) =8841627a(13) =46015002a(14) =241394073a(15) =1275137448a(16) =6776728825a(17) =36208438488a(18) =194388488155