This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A380243 #8 Jan 22 2025 17:32:52 %S A380243 1,54,3000,171500,10001880,591666768,35371207872,2131746903000, %T A380243 129299660919000,7883256659941520,482689850761774656, %U A380243 29661047546558142624,1828220386252351000000,112982297841774018000000,6998159395715622920640000,434337846995341921726638000,27004842919501042631643927000 %N A380243 Number of rooted 2n-regular planar maps with 3 vertices. %C A380243 There are no odd valent regular planar maps with 3 vertices. %H A380243 Andrew Howroyd, <a href="/A380243/b380243.txt">Table of n, a(n) for n = 1..200</a> %F A380243 a(n) = n*binomial(2*n-1, n)^3. %F A380243 a(n) = n*A002897(n - 1). %o A380243 (PARI) a(n) = n*binomial(2*n-1, n)^3 %Y A380243 Row n=3 of A380241. %Y A380243 Cf. A000984, A002897, A380242. %K A380243 nonn %O A380243 1,2 %A A380243 _Andrew Howroyd_, Jan 22 2025