The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A294672 Number of disjoint covering systems of cardinality n, up to equivalence under shift. 1
 1, 1, 2, 4, 10, 26, 75, 226, 718, 2368, 8083, 28367 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS A disjoint covering system is a system of n congruences x == a_i (mod m_i) such that every integer is a solution to exactly one of the congruences. This sequence counts them up to "shift"; that is, two systems are the same if we can turn one into another by subtracting a constant from x. LINKS B. Novak and S. Znam, Disjoint Covering Systems, The American Mathematical Monthly, Vol. 81, No. 1 (1974), 42-45. Wikipedia, Covering system EXAMPLE For n = 3 there are three disjoint covering systems: (a) x == 0 (mod 3), x == 1 (mod 3), x == 2 (mod 3) (b) x == 0 (mod 2), x == 1 (mod 4), x == 3 (mod 4) (c) x == 1 (mod 2), x == 0 (mod 4), x == 2 (mod 4) but (b) and (c) are equivalent under shift. CROSSREFS Sequence in context: A006123 A006251 A049401 * A239077 A148099 A007579 Adjacent sequences:  A294669 A294670 A294671 * A294673 A294674 A294675 KEYWORD nonn,more AUTHOR Jeffrey Shallit, Nov 06 2017 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 22 05:13 EST 2021. Contains 340360 sequences. (Running on oeis4.)