Convolution of the Catalan numbers A000108(n) and (-2)^n.

Terms

a(0) =1a(1) =-1a(2) =4a(3) =-3a(4) =20a(5) =2a(6) =128a(7) =173a(8) =1084a(9) =2694a(10) =11408a(11) =35970a(12) =136072a(13) =470756a(14) =1732928a(15) =6228989a(16) =22899692a(17) =83845406a(18) =309947888a(19) =1147367414a(20) =4269385592a(21) =15927495836a(22) =59627571968a(23) =223804469714a(24) =842295207896