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 A063628 #6 Jun 26 2018 19:07:22
%S A063628 1,3,15,12,28,26,30,39,70,50,54,82,93,106,105,80,110,121,130,135,156,
%T A063628 175,173,183,174,211,194,264,158,216,285,251,306,262,308,298,263,322,
%U A063628 346,323,354,276,375,380,419,350,404,432,384,465,403
%N A063628 Smallest k such that 9^k has exactly n 2's in its decimal representation.
%t A063628 a = {}; Do[k = 1; While[ Count[ IntegerDigits[9^k], 2] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
%K A063628 base,nonn
%O A063628 0,2
%A A063628 _Robert G. Wilson v_, Aug 10 2001
%E A063628 Name corrected by _Jon E. Schoenfield_, Jun 26 2018