Array read by antidiagonals: T(n,k) is the number of isomorphism classes of n-fold coverings of a connected graph with Betti number k (1 <= n, 0 <= k).

A160449

Array read by antidiagonals: T(n,k) is the number of isomorphism classes of n-fold coverings of a connected graph with Betti number k (1 <= n, 0 <= k).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =1a(6) =1a(7) =3a(8) =4a(9) =1a(10) =1a(11) =5a(12) =11a(13) =8a(14) =1a(15) =1a(16) =7a(17) =43a(18) =49a(19) =16a(20) =1a(21) =1a(22) =11a(23) =161a(24) =681a(25) =251a(26) =32a(27) =1a(28) =1a(29) =15

External references