Triangle read by rows: T(n,k) is the number of involutions of {1,2,...,n} having genus k (see first comment for definition of genus).

A178515

Triangle read by rows: T(n,k) is the number of involutions of {1,2,...,n} having genus k (see first comment for definition of genus).

Terms

    a(0) =1a(1) =2a(2) =0a(3) =4a(4) =0a(5) =0a(6) =9a(7) =1a(8) =0a(9) =0a(10) =21a(11) =5a(12) =0a(13) =0a(14) =0a(15) =51a(16) =25a(17) =0a(18) =0a(19) =0a(20) =0a(21) =127a(22) =105a(23) =0a(24) =0a(25) =0a(26) =0a(27) =0a(28) =323a(29) =420

External references