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 A215736 #30 Jul 20 2024 08:12:35
%S A215736 1,1,7,9,5,7,3,1,0,0,3,4,6,5,9,1
%N A215736 a(n) is the first digit to appear n times in succession in a power of 7.
%t A215736 n = 1; x = 1; lst = {};
%t A215736 For[i = 1, i <= 10000, i++,
%t A215736 z = Split[IntegerDigits[x]]; a = Length /@ z; b = Max[a];
%t A215736 For[j = n, j <= b, j++,
%t A215736 AppendTo[lst, First[First[Part[z, First[Position[a, b]]]]]]; n++
%t A215736 ]; x = 7 x ]; lst (* _Robert Price_, Mar 16 2019 *)
%Y A215736 Cf. A215730, A045875, A215732.
%K A215736 nonn,base,hard,more
%O A215736 1,3
%A A215736 _V. Raman_, Aug 22 2012
%E A215736 a(10) added by _V. Raman_, Nov 23 2013
%E A215736 a(11)-a(13) from _Giovanni Resta_, Apr 19 2016
%E A215736 a(14)-a(15) from _Bert Dobbelaere_, Feb 15 2019
%E A215736 a(16) from _Paul Geneau de Lamarlière_, Jul 16 2024