A380625 Number of rooted regular combinatorial maps with n edges.

1, 2, 4, 21, 130, 1135, 12448, 154441, 2283922, 38761556, 721082359, 14999247901, 345288253975, 8513996163751, 228807509644648, 6634125686206751, 203954623297226722, 6705169274925371251, 234777003656354137054, 8632415297513570062501, 335879068944350793715480

Offset: 0

Author

Andrew Howroyd, Jan 29 2025

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..200

Crossrefs

Cf. A380622.

Programs

PARI

a(n)={if(n==0, 1, sumdiv(2*n, d, T(d,2*n/d)))} \\ T(n,k) defined in A380622.

Formula

a(n) = Sum_{d|2*n} A380622(d,2*n/d) for n > 0.