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 A051238 #19 Feb 16 2025 08:32:41
%S A051238 3,1,18,11,12,21,2,4,13,196,201,371,28,224,202,95,89,3,109,112,88,253,
%T A051238 17,34,93,31,1,5,132,72,190,111,143,144,18,20,271,86,107,67,125,98,
%U A051238 135,240,11,104,26,229,35,236,94,16,19,77,302,154,39,326,12,21
%N A051238 First appearance of string n in e.
%C A051238 A088576 has the a(0) term.
%H A051238 T. D. Noe, <a href="/A051238/b051238.txt">Table of n, a(n) for n = 1..10000</a>
%H A051238 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/eDigits.html">e Digits</a>
%t A051238 (* Computing 200000 digits of e is sufficient up to n=10000 *) eString = RealDigits[E, 10, 200000] // First // ToString /@ # & // StringJoin; a[n_] := (p = StringPosition[eString, n // ToString, 1]; If[p == {}, 0, p[[1, 1]]]); Table[a[n], {n, 1, 60}] (* _Jean-François Alcover_, Mar 04 2013 *)
%t A051238 With[{eee=RealDigits[E,10,200000][[1]]},Transpose[Flatten[Table[ SequencePosition[ eee,IntegerDigits[n],1],{n,70}],1]][[1]]] (* The program uses the SequencePosition function from Mathematica version 10 *) (* _Harvey P. Dale_, Nov 20 2015 *)
%Y A051238 Cf. A001113 (decimal expansion of e).
%Y A051238 Cf. A088576 (same as a(n) but including the term for n = 0).
%Y A051238 Cf. A032445.
%K A051238 base,easy,nice,nonn
%O A051238 1,1
%A A051238 _Harvey P. Dale_