A024949 a(n) = Sum(a(2i-1)*a(n-2i+1), i = 1,2,...,[ (n+2)/4 ]).

1, 1, 4, 4, 4, 20, 36, 52, 132, 292, 580, 1252, 2628, 6772, 14820, 32404, 75012, 183108, 423428, 953924, 2225028, 5435604, 12770340, 29545076, 69900164, 170528612, 405553988, 954683428, 2267938244, 5585542964, 13382224612, 31793247188