a(n) is the number of 2n-regular circulant graphs of order 53.

Terms

a(0) =1a(1) =1a(2) =13a(3) =100a(4) =578a(5) =2530a(6) =8866a(7) =25300a(8) =60115a(9) =120175a(10) =204347a(11) =297160a(12) =371516a(13) =400024a(14) =371516a(15) =297160a(16) =204347a(17) =120175a(18) =60115a(19) =25300a(20) =8866a(21) =2530a(22) =578a(23) =100a(24) =13a(25) =1a(26) =1