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 A246747 #48 Nov 10 2024 14:49:19
%S A246747 1,1,1,2,3,7,14,37,80,222,544,1601,4095,12416,33785,105769,293747,
%T A246747 935184,2717376,8848014,26134254,86210716,262068267,877833206,
%U A246747 2695238060,9109101156,28619396967,97879220771,310021153392,1067906857449,3440140082033,11957123227292
%N A246747 The number of binary heaps on n elements whose breadth-first search reading word avoids 231.
%C A246747 Also, the number of binary heaps on n elements whose breadth-first search reading word avoids 312.
%C A246747 Note that a breadth-first search reading word is equivalent to reading the tree labels left to right by levels, starting with the root.
%C A246747 For more information on heaps, see A056971.
%H A246747 Alois P. Heinz, <a href="/A246747/b246747.txt">Table of n, a(n) for n = 0..1000</a>
%H A246747 D. Levin, L. Pudwell, M. Riehl, A. Sandberg, <a href="http://www.etsu.edu/cas/math/pp2014/documents/talks/riehl.pdf">Pattern Avoidance on k-ary Heaps</a>, Slides of Talk, 2014.
%H A246747 Manda Riehl (joint work with Derek Levin, Lara Pudwell, and Adam Sandberg), <a href="/A246747/a246747_1.png">Page 92 of the Permutation Patterns 2014 Abstract Book </a>.
%H A246747 Manda Riehl, <a href="/A246747/a246747.png">A heap on 4 elements</a>
%F A246747 a(n) = Sum_{i=0..floor((n-1)/2)} A000108(i)*a(n-i-1) for n > 0.
%e A246747 A heap on 4 elements is pictured in the 2nd link, and has breadth first reading word abcd. Then for n = 4 the a(4) = 3 heaps have reading words 1234, 1243, and 1324.
%Y A246747 May be equal to A245899.
%Y A246747 Cf. A000108, A056971, A246829.
%K A246747 nonn
%O A246747 0,4
%A A246747 _Manda Riehl_, Sep 04 2014