a(n) = A152534(n,n).

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =8a(5) =42a(6) =215a(7) =964a(8) =4336a(9) =18490a(10) =78920a(11) =327422a(12) =1361450a(13) =5561651a(14) =22748172a(15) =92064605a(16) =372730314a(17) =1498785098a(18) =6028277742a(19) =24137078144a(20) =96650940881a(21) =385889337069