Diagonal sums of number array A107249.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =9a(6) =16a(7) =30a(8) =54a(9) =104a(10) =191a(11) =372a(12) =692a(13) =1357a(14) =2550a(15) =5021a(16) =9508a(17) =18773a(18) =35766a(19) =70755a(20) =135461a(21) =268365a(22) =515849a(23) =1023092a(24) =1973159a(25) =3916831a(26) =7575470a(27) =15048428a(28) =29175431a(29) =57990158