cp's OEIS Frontend

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.

A232620 Numbers k such that (2k)!! mod (2k-1)!! is greater than (2k+2)!! mod (2k+1)!!.

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%I A232620 #20 Dec 22 2024 10:33:32
%S A232620 4,615,9090,11011
%N A232620 Numbers k such that (2k)!! mod (2k-1)!! is greater than (2k+2)!! mod (2k+1)!!.
%C A232620 Numbers k such that A232618(k) > A232618(k+1).
%C A232620 a(5) > 10 * 2^20.
%e A232620 4 is in the sequence because A232618(4) > A232618(5).
%o A232620 (Python)
%o A232620 o=e=1  # odd, even
%o A232620 prev=0
%o A232620 for n in range(1,1000000000,2):
%o A232620   o*=n
%o A232620   e*=n+1
%o A232620   cur = e%o
%o A232620   if prev>cur: print(str(n//2), end=', ')
%o A232620   prev=cur
%Y A232620 Cf. A006882, A232618.
%K A232620 nonn,hard,more
%O A232620 1,1
%A A232620 _Alex Ratushnyak_, Nov 27 2013