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

4, 615, 9090, 11011

Offset: 1

Author

Alex Ratushnyak, Nov 27 2013

Keywords

• nonn
• hard
• more

Comments

Numbers k such that A232618(k) > A232618(k+1).

a(5) > 10 * 2^20.

Examples

			4 is in the sequence because A232618(4) > A232618(5).
		

Crossrefs

Cf. A006882, A232618.

Programs

Python

o=e=1  # odd, even
prev=0
for n in range(1,1000000000,2):
  o*=n
  e*=n+1
  cur = e%o
  if prev>cur: print(str(n//2), end=', ')
  prev=cur