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 A331881 #18 Feb 28 2020 23:03:25 %S A331881 1,26,446,2796,86538,872117,1591292,66416662 %N A331881 a(n) is the first n-digit substring to occur n times in the decimal expansion of the fractional part of Pi. %e A331881 a(1) = 1, because '1' is the first 1-digit string appearing 1 time (at position 1); %e A331881 a(2) = 26, because '26' is the first 2-digit string appearing 2 times (at positions 6 and 21); %e A331881 a(3) = 446, because '446' is the first 3-digit string appearing 3 times (at positions 125, 182 and 217); %e A331881 and so on. %Y A331881 Cf. A000796, A197123. %Y A331881 Cf. A331882 (the number of digits needed to find the repeated n-digit strings). %K A331881 base,nonn,hard,more %O A331881 1,2 %A A331881 _Stijn Dierckx_, Jan 30 2020