cp's OEIS Frontend

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.

A341920 Number of simple strong triangulations of a fixed pentagon with n interior nodes.

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%I A341920 #14 Feb 08 2022 12:13:06
%S A341920 1,5,20,85,385,1836,9120,46805,246675,1328925,7292688,40652780,
%T A341920 229698220,1313175880,7585060680,44212723797,259808593975,
%U A341920 1537840085775,9162371040900,54913015836525,330888232445505,2003659057873200,12187811305300800,74444226847892460,456458831442283860
%N A341920 Number of simple strong triangulations of a fixed pentagon with n interior nodes.
%H A341920 Andrew Howroyd, <a href="/A341920/b341920.txt">Table of n, a(n) for n = 1..500</a>
%F A341920 From _Peter Bala_, Feb 06 2022: (Start)
%F A341920 Conjectures:
%F A341920 a(n) = 5*(5*n-3)*binomial(3*n,n)/((n+1)*(2*n+1)*(2*n+3)).
%F A341920 a(n+1) = 3*(3*n+1)*(3*n+2)*(5*n+2)/(2*(n+2)*(2*n+5)*(5*n-3))*a(n). (End)
%o A341920 (PARI) R(25,2) \\ R defined in A210664.
%Y A341920 Row m = 2 of A210664.
%Y A341920 Cf. A000256, A341917.
%K A341920 nonn
%O A341920 1,2
%A A341920 _Andrew Howroyd_, Feb 24 2021