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 A332263 #14 Feb 09 2020 10:41:21 %S A332263 3,7,12,17,22,30,39,45,56,66,77,90 %N A332263 Maximal length of a string over the alphabet {0,1,2} with the property that its contiguous substrings of length n all have different quantities of 0's, 1's, or 2's. %C A332263 In other words, the contiguous substrings of length n are all different if we interpret them as multisets. %C A332263 Since there are binomial(n+2,2) different triples of nonnegative integers summing up to n, we have the bound a(n) <= binomial(n+2,2)+n-1. Equality holds if and only if n <= 3. %H A332263 Bert Dobbelaere, <a href="/A332263/a332263.cpp.txt">C++ program</a> %H A332263 MathOverflow, <a href="https://mathoverflow.net/questions/268428/sequences-with-3-letters">Sequences with 3 Letters</a> %e A332263 Maximal strings for n = 1, 2, ..., 8 are: %e A332263 012 %e A332263 0011220 %e A332263 011122200012 %e A332263 00111122220000121 %e A332263 0100212111000002222211 %e A332263 001011112122220200001012120200 %e A332263 010010220212110100000202222212111110100 %e A332263 021200201101121220202000010111111212222220200 %K A332263 nonn,more,hard %O A332263 1,1 %A A332263 _Nathaniel Johnston_, Feb 08 2020 %E A332263 a(9)-a(12) from _Bert Dobbelaere_, Feb 09 2020