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 A049305 #22 Feb 01 2025 23:19:33 %S A049305 3,4,6,8,12,15,20,40,42,43,50,53,55,59,60,61,62,69,72,73,74,75,78,79, %T A049305 80,81,83,86,87,88,89,93,94,95,96,97,99,100,103,111,113,114,118,164, %U A049305 165,185,193,200,207,210,215,220,230,232,238,241,243,250,253,254,255 %N A049305 Numbers k such that k is a substring of 7^k. %o A049305 (Python) %o A049305 def ok(n): return str(n) in str(7**n) %o A049305 print(list(filter(ok, range(256)))) # _Michael S. Branicky_, Aug 13 2021 %Y A049305 Cf. A000420, A032740, A049301, A049302, A049303, A049304, A049306, A049307. %K A049305 nonn,base,easy %O A049305 1,1 %A A049305 _David W. Wilson_