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 A086077 #9 Apr 19 2022 18:16:39 %S A086077 0,0,0,1,0,0,0,0,1,0,0,2,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,1,0,1,1,0,1, %T A086077 0,1,3,0,0,0,0,1,0,1,0,0,0,0,1,0,0,1,0,0,0,0,1,1,0,0,0,0,0,1,0,0,0,0, %U A086077 1,0,0,1,1,0,0,0,1,0,0,1,0,0,0,1,0,1,0,0,1,0,0,1,0,0,1,1,2,0,0,0,0,0,0,1,1 %N A086077 Number of 6's in decimal expansion of triangular number n(n+1)/2. %H A086077 Harvey P. Dale, <a href="/A086077/b086077.txt">Table of n, a(n) for n = 0..1000</a> %t A086077 DigitCount[#,10,6]&/@Accumulate[Range[0,120]] (* _Harvey P. Dale_, Apr 19 2022 *) %Y A086077 Cf. 0's A086071, 1's A086072, 2's A086073, 3's A086074, 4's A086075, 5's A086076, 7's A086078, 8's A086079, 9's A086080. %K A086077 base,nonn %O A086077 0,12 %A A086077 _Jason Earls_, Jul 08 2003