A123298 Number of incongruent restricted disjoint covering systems (IRDCS) of length n.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 4, 6, 18, 14, 26, 84, 88, 46, 176, 380, 812, 844, 1770, 2164, 5554, 9244, 25384, 62092, 68176, 85762, 304892, 855072, 1229050, 1805096

Offset

1,11

Comments

An IRDCS of length n is a sequence of n integers s(1),...,s(n) with the property that if s(i)=m for some m then the other terms of the sequence with value m are precisely s(i+k*m) for all k such that i+k*m is in [1,n] and further such that any integer appearing in the sequence appears at least twice. For example, the two IRDCS of length n are 6,9,3,4,5,3,6,4,3,5,9 and its reverse.

References

Gerry Myerson, Jacky Poon and Jamie Simpson, Incongruent restricted disjoint covering systems, preprint.

Links

Table of n, a(n) for n=1..40.

Crossrefs

Sequence in context: A213902 A170770 A107499 * A189877 A189868 A336104

Adjacent sequences: A123295 A123296 A123297 * A123299 A123300 A123301

Keyword

nice,nonn

Author

Jamie Simpson, Jun 25 2007, corrected Sep 11 2007

Status

approved