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 A084420 #51 Mar 09 2024 04:50:44
%S A084420 3,14,103,1042,10158,100502,1000617,10006509,100019088,1000004377,
%T A084420 10000170793,100000442970,1000001981666,10000005339905,
%U A084420 100000018997256,1000000065392525,10000000201014294,100000000631520633,1000000001077349719,10000000005309690910
%N A084420 Least number k such that between k! and (k+1)! there are n powers of ten.
%H A084420 Kevin Ryde, <a href="/A084420/b084420.txt">Table of n, a(n) for n = 1..400</a>
%H A084420 Kevin Ryde, <a href="/A084420/a084420.c.txt">C code</a>.
%t A084420 LogBase10Stirling[n_] := Floor[ Log[10, 2 Pi n]/2 + n * Log[10, n/E] + Log[10, 1 + 1/(12n) + 1/(288n^2) - 139/(51840n^3) - 571/(2488320n^4) + 163879/(209018880n^5)]]; Do[k = 10^(n - 1); While[ LogBase10Stirling[k + 1] - LogBase10Stirling[k] < n, k++ ]; a[n] = k; Print[ a[n]], {n, 1, 14}]
%o A084420 (C) /* See links. */
%Y A084420 Cf. A084321.
%K A084420 nonn
%O A084420 1,1
%A A084420 _Robert G. Wilson v_, Jun 26 2003
%E A084420 a(15)-a(20) from _Kevin Ryde_, Mar 09 2024