G.f. of the z^1 coefficients of the FP1 in the second column of the A156921 matrix.

Terms

a(0) =1a(1) =7a(2) =28a(3) =86a(4) =227a(5) =545a(6) =1230a(7) =2664a(8) =5613a(9) =11611a(10) =23728a(11) =48106a(12) =97031a(13) =195077a(14) =391394a(15) =784284a(16) =1570353a(17) =3142815a(18) =6288100a(19) =12579070a(20) =25161451a(21) =50326697a(22) =100657718a(23) =201320336a(24) =402646197a(25) =805298595