Third diagonal of A027516.

Terms

a(0) =11a(1) =26a(2) =121a(3) =558a(4) =1178a(5) =784a(6) =567a(7) =397a(8) =1166a(9) =845a(10) =31965a(11) =425752a(12) =647962a(13) =489749a(14) =188365a(15) =289264a(16) =1577216a(17) =23292216a(18) =18324228a(19) =2405956350a(20) =239597946294a(21) =45293834608