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 A083631 #16 Feb 16 2025 08:32:49
%S A083631 1589,1590,4575,5241,5242,5322,5323,5355,5450,5863,5864,11298,11733,
%T A083631 12661,14292,15501,17234,17502,18516,19903,20404,21423,21571,23538,
%U A083631 23749,24373,25551,25788,25858,26796,29504,29505,30988,32478,32479
%N A083631 Starting positions of strings of three 7's in the decimal expansion of Pi.
%C A083631 Position counted from and after decimal point. - _Harvey P. Dale_, Mar 13 2023
%H A083631 <a href="/index/Ph#Pi314">Index entries for sequences related to the number Pi</a>
%H A083631 Dave Andersen, <a href="http://www.angio.net/pi/piquery">Pi-Search Page</a>
%H A083631 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PiDigits.html">Pi Digits.</a>
%t A083631 q=9!;z=7;a=RealDigits[Pi,10,q];lst={};Do[b=a[[1]][[n]];c=a[[1]][[n+1]];d=a[[1]][[n+2]];If[b==z&&c==z&&d==z,AppendTo[lst,n-1]],{n,q-2}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jun 19 2009 *)
%t A083631 SequencePosition[RealDigits[Pi,10,33000][[1]],{7,7,7}][[;;,1]]-1 (* _Harvey P. Dale_, Mar 13 2023 *)
%Y A083631 Cf. A050254 (two 7's), A083632 (four 7's).
%K A083631 base,nonn
%O A083631 1,1
%A A083631 _Rick L. Shepherd_, May 04 2003