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.

A341439 Table of generalized ménage numbers read by antidiagonals upward: T(n,k) is the number of permutations pi in S_k such that pi(i) != i, i+n (mod k) for all i; n, k >= 1.

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 0, 0, 1, 2, 0, 1, 2, 4, 13, 0, 0, 1, 2, 13, 80, 0, 1, 1, 9, 13, 82, 579, 0, 0, 2, 2, 13, 80, 579, 4738, 0, 1, 1, 4, 44, 82, 579, 4740, 43387, 0, 0, 1, 2, 13, 80, 579, 4738, 43387, 439792, 0, 1, 2, 9, 13, 265, 579, 4752, 43390, 439794, 4890741
Offset: 1

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Author

Peter Kagey, Feb 11 2021

Keywords

Comments

The recurrence for the second row comes from Doron Zeilberger's MENAGE program, available via the arXiv reference.

Examples

			Table begins:
n\k | 1 2 3 4  5   6    7     8
----+--------------------------
  1 | 0 0 1 2 13  80  579  4738
  2 | 0 1 1 4 13  82  579  4740
  3 | 0 0 2 2 13  80  579  4738
  4 | 0 1 1 9 13  82  579  4752
  5 | 0 0 1 2 44  80  579  4738
  6 | 0 1 2 4 13 265  579  4740
  7 | 0 0 1 2 13  80 1854  4738
  8 | 0 1 1 9 13  82  579 14833
		

Crossrefs

Formula

T(n,n) = A000166(n) for n >= 1.
T(1,k) = A000179(k).
T(k-1,k) = A000179(k) for k >= 2.
T(n,k) = T(n+k, k).
T(2,k) = k*T(2,k-1) + 3*T(2,k-2) + (-2*k+6)*T(2,k-3) - 3*T(2,k-4) + (k-6)*T(2,k-5) + T(2,k-6) for k > 8.
T(n,k) = A277256(gcd(n,k),k/gcd(n,k)). - Pontus von Brömssen, May 31 2022