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 A062504 #16 Jan 08 2021 12:59:46 %S A062504 1,2,3,4,5,6,7,8,9,16,10,11,12,13,14,17,18,19,23,25,27,32,49,53,64,81, %T A062504 128,256,512,65536,15,20,21,22,24,26,28,29,31,34,36,37,38,41,43,46,48, %U A062504 50,54,59,61,67,83,97,98,103,106,121,125,131,162,169,227,241,243,289 %N A062504 Triangle in which k-th row lists natural number values for the collection of riffs with k nodes. %H A062504 Jon Awbrey, <a href="https://oeis.org/wiki/Riffs_and_Rotes">Riffs and Rotes</a> %H A062504 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %e A062504 k | natural numbers n such that |riff(n)| = k %e A062504 0 | 1; %e A062504 1 | 2; %e A062504 2 | 3, 4; %e A062504 3 | 5, 6, 7, 8, 9, 16; %e A062504 4 | 10, 11, 12, 13, 14, 17, 18, 19, 23, 25, 27, 32, 49, 53, 64, 81, 128, 256, 512, 65536; %e A062504 The natural number values for the riffs with at most 3 pts are as follows (x = root): %e A062504 .................o.......o..o.......o %e A062504 .................|.......^..|.......^ %e A062504 .................v.......|..v.......| %e A062504 ...........o..o..o....o..o..o..o.o..o %e A062504 ...........|..^..|....|..|..^..|.^..^ %e A062504 ...........v..|..v....v..v..|..v/...| %e A062504 Riff:...x;.x,.x;.x,.x.x,.x,.x,.x,...x; %e A062504 Value:..2;.3,.4;.5,..6.,.7,.8,.9,..16; %Y A062504 Cf. A061396, A062860. %K A062504 nonn,tabf %O A062504 0,2 %A A062504 _Jon Awbrey_, Jun 23 2001