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 A114853 #9 Jul 29 2023 14:33:19
%S A114853 1,2,9,32,208,972,7843,43690,409968,2604166,27447010,193491763,
%T A114853 2241278030,17224712961,216027868615,1787142709274,24006211998207,
%U A114853 211773735868781,3021737893128258,28218694885361552,424936725846414486
%N A114853 a(n) = floor(n^n/n!!).
%C A114853 This is to double factorial A006882 as A055775 "Floor(n^n/n!)" is to factorial. This sequence is a weak first approximation of a double factorial analog to Stirling's approximation to factorial. Note that a(n) is exact for n = 1, 2, 3, 4, 6.
%F A114853 a(n) = floor(n^n/n!!). a(n) = floor(A000312(n)/A006882(n)).
%e A114853 a(10) = floor((10^10)/3840) = floor(2604166.67) = 2604166.
%p A114853 A114853 := proc(n)
%p A114853 n^n/doublefactorial(n) ;
%p A114853 floor(%) ;
%p A114853 end proc:
%p A114853 seq(A114853(n),n=1..25) ; # _R. J. Mathar_, Jun 23 2014
%t A114853 Table[Floor[n^n/n!!],{n,30}] (* _Harvey P. Dale_, Jul 29 2023 *)
%Y A114853 Cf. A000312, A006882, A055775.
%K A114853 easy,nonn
%O A114853 1,2
%A A114853 _Jonathan Vos Post_, Feb 20 2006