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 A028902 #7 Jul 08 2025 18:55:07 %S A028902 0,1,2,3,4,5,6,7,8,9,7,8,9,10,11,12,13,14,15,16,14,15,16,17,18,19,20, %T A028902 21,22,23,21,22,23,24,25,26,27,28,29,30,28,29,30,31,32,33,34,35,36,37, %U A028902 35,36,37,38,39,40,41,42,43,44,42,43,44,45,46,47,48,49,50,51,49,50,51,52 %N A028902 Map n = Sum c_i 10^i to a(n) = Sum c_i 7^i. %K A028902 nonn,base %O A028902 0,3 %A A028902 _N. J. A. Sloane_ %E A028902 More terms from _Erich Friedman_.