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A232863
Numbers k such that (2*k-1)!! mod k! is greater than (2k+1)!! mod (k+1)!.
0
16, 75, 82, 572, 5260, 33232, 99589, 200413, 2940392
OFFSET
1,1
COMMENTS
Numbers k such that A232701(k) > A232701(k+1).
(2k-1)!! is the product of first k odd numbers.
EXAMPLE
16 is in the sequence because A232701(16) > A232701(17).
MATHEMATICA
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 *)
PROG
(Python)
o = f = 1
prev = 0
for n in range(1, 1000000):
o *= 2*n-1
f *= n
cur = o % f
if prev>cur: print str(n-1)+', ',
prev=cur
if (n&8191)==0: print '.',
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Alex Ratushnyak, Dec 01 2013
STATUS
approved