Diagonal sums of Riordan array (1/(1+x),x(1+x)/(1-x)).

Terms

a(0) =1a(1) =-1a(2) =2a(3) =0a(4) =3a(5) =3a(6) =8a(7) =12a(8) =25a(9) =43a(10) =82a(11) =148a(12) =275a(13) =503a(14) =928a(15) =1704a(16) =3137a(17) =5767a(18) =10610a(19) =19512a(20) =35891a(21) =66011a(22) =121416a(23) =223316a(24) =410745a(25) =755475a(26) =1389538a(27) =2555756a(28) =4700771a(29) =8646063