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 A083642 #21 Feb 18 2025 16:09:05
%S A083642 762,763,764,765,2949,7759,8527,9962,11197,11382,13019,16687,17119,
%T A083642 17561,17988,17989,18680,19437,19438,19446,19447,19448,19748,21579,
%U A083642 22309,22753,22754,23989,24107,25584,26069,26490,27602,28122,28320
%N A083642 Starting positions of strings of three 9's in the decimal expansion of Pi.
%H A083642 Harvey P. Dale, <a href="/A083642/b083642.txt">Table of n, a(n) for n = 1..1000</a>
%H A083642 <a href="/index/Ph#Pi314">Index entries for sequences related to the number Pi</a>
%H A083642 Dave Andersen, <a href="http://www.angio.net/pi/piquery">Pi-Search Page</a>
%H A083642 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PiDigits.html">Pi Digits.</a>
%t A083642 Transpose[ StringPosition[ StringDrop[ ToString[ N[Pi, 28588]], 2], "999"]][[1]]
%t A083642 Flatten[With[{p=Partition[RealDigits[Pi,10,30000][[1]],3,1]},Position[p,{9,9,9}]]]-1 (* _Harvey P. Dale_, Jan 05 2013 *)
%t A083642 With[{pid=RealDigits[Pi,10,30000][[1]]},SequencePosition[pid,{9,9,9}]][[;;,1]]-1 (* _Harvey P. Dale_, Feb 18 2025 *)
%Y A083642 Cf. A050272 (two 9's), A083643 (four 9's).
%K A083642 base,nonn
%O A083642 1,1
%A A083642 _Rick L. Shepherd_, May 05 2003