Diagonal sums of number triangle A104881.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =8a(6) =14a(7) =24a(8) =45a(9) =85a(10) =170a(11) =351a(12) =749a(13) =1656a(14) =3758a(15) =8776a(16) =21013a(17) =51473a(18) =129018a(19) =329939a(20) =860901a(21) =2288528a(22) =6192526a(23) =17047248a(24) =47693661a(25) =135554549a(26) =391099370a(27) =1144867871a(28) =3398656893a(29) =10226072720