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.

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A232863 Numbers k such that (2*k-1)!! mod k! is greater than (2k+1)!! mod (k+1)!.

Original entry on oeis.org

16, 75, 82, 572, 5260, 33232, 99589, 200413, 2940392
Offset: 1

Views

Author

Alex Ratushnyak, Dec 01 2013

Keywords

Comments

Numbers k such that A232701(k) > A232701(k+1).
(2k-1)!! is the product of first k odd numbers.

Examples

			16 is in the sequence because A232701(16) > A232701(17).
		

Crossrefs

Programs

  • 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 *)
  • 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(n-1, end=', ')
      prev=cur
      if (n&8191)==0: print('.', end=', ')
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