A343093 Number of rooted toroidal maps with n edges and no isthmuses.

1, 14, 159, 1680, 17147, 171612, 1696491, 16631840, 162090756, 1572801142, 15210259585, 146710561296, 1412132981778, 13569013500024, 130199055578307, 1247825314752768, 11947157409479180, 114288613130155608, 1092495810452593564, 10436544808441964352

Offset: 2

Author

Andrew Howroyd, Apr 04 2021

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 2..100

Crossrefs

Row sums of A343092.

Cf. A224274, A343091.

Formula

Conjectural g.f.: A(x) = ( Sum_{n >= 1} (1/4)*binomial(4*n, n)*x^n )^2. - Peter Bala, Jul 24 2025