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 A232863 #21 Jul 31 2025 14:31:23
%S A232863 16,75,82,572,5260,33232,99589,200413,2940392
%N A232863 Numbers k such that (2*k-1)!! mod k! is greater than (2k+1)!! mod (k+1)!.
%C A232863 Numbers k such that A232701(k) > A232701(k+1).
%C A232863 (2k-1)!! is the product of first k odd numbers.
%e A232863 16 is in the sequence because A232701(16) > A232701(17).
%t A232863 o = 1; prev = cur = 0; Reap[For[n = 1, n < 3*10^6, n += 2, o *= n; prev = cur; cur = Mod[o, (Quotient[n, 2] + 1)!]; If[n > 1 && prev > cur, Print[(n - 1)/2]; Sow[(n - 1)/2]]]][[2, 1]] (* translated from _Alex Ratushnyak_'s Python code *)
%o A232863 (Python)
%o A232863 o = f = 1
%o A232863 prev = 0
%o A232863 for n in range(1,1000000):
%o A232863 o *= 2*n-1
%o A232863 f *= n
%o A232863 cur = o % f
%o A232863 if prev>cur: print(n-1, end=', ')
%o A232863 prev=cur
%o A232863 if (n&8191)==0: print('.', end=', ')
%Y A232863 Cf. A000142, A006882, A232620, A232701.
%K A232863 nonn,hard,more
%O A232863 1,1
%A A232863 _Alex Ratushnyak_, Dec 01 2013