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 A043518 #14 Jul 30 2022 16:43:16 %S A043518 77,177,277,377,477,577,677,707,717,727,737,747,757,767,770,771,772, %T A043518 773,774,775,776,778,779,787,797,877,977,1077,1177,1277,1377,1477, %U A043518 1577,1677,1707,1717,1727,1737,1747,1757,1767,1770,1771 %N A043518 Numbers having two 7's in base 10. %H A043518 Daniel Starodubtsev, <a href="/A043518/b043518.txt">Table of n, a(n) for n = 1..10000</a> %t A043518 Select[Range[2000],DigitCount[#,10,7]==2&] (* _Harvey P. Dale_, Jul 30 2022 *) %Y A043518 Subsequence of A011537. %K A043518 nonn,base %O A043518 1,1 %A A043518 _Clark Kimberling_