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.

User: Jeffrey Davis

Jeffrey Davis's wiki page.

Jeffrey Davis has authored 2 sequences.

A260752 Number of prime juggling patterns of period n using 5 balls.

Original entry on oeis.org

1, 5, 29, 157, 901, 4822, 27447, 149393, 836527, 4610088, 25846123, 142296551, 799268609, 4426204933, 24808065829, 137945151360, 773962487261, 4310815784117, 24208263855765
Offset: 1

Author

Jeffrey Davis, Jul 30 2015

Keywords

Comments

A juggling pattern is prime if the closed walk corresponding to the pattern in the juggling state graph is a cycle.

Examples

			In siteswap notation, the prime juggling pattern(s) of length one is 5; of length two are 64, 73, 82, 91 and (10)0; of length three are (11)31, (11)22, 4(10)1, 3(12)0, (13)20, (13)11, 591, (10)23, (10)41, 960, 780, 663, 744, 753, 4(11)0, (12)12, (12)30, 771, 861, (15)00, 933, 942, 582, (10)50, 690, (14)01, 852, 834 and 672.
		

Crossrefs

Extensions

a(12)-a(13) from Roman Berens, Mar 20 2021
a(14)-a(19) from Jack Boyce, May 31 2024

A260585 Number of ways to place 2n rooks on an n X n board, with 2 rooks in each row and each column, multiple rooks in a cell allowed, and exactly 2 rooks below the main diagonal.

Original entry on oeis.org

1, 11, 72, 367, 1630, 6680, 26082, 98870, 368045, 1354850, 4953503, 18035279, 65499031, 237511321, 860471110, 3115667369, 11277816388, 40814611818, 147692103728, 534404499040, 1933597628291, 6996040095316, 25312367524557, 91581960107817, 331348634005165
Offset: 2

Author

Jeffrey Davis, Jul 29 2015

Keywords

Comments

a(n) is the number of minimal multiplex juggling patterns of period n using exactly 2 balls when we can catch/throw up to 2 balls at a time. (Minimal in the sense that each of the n throws is between 0 and n-1.)

Crossrefs

Column k=2 of A269742.

Programs

  • Mathematica
    CoefficientList[Series[-(5*x^4 - 3*x^3 - x^2 - x + 1)/(20*x^7 - 100*x^6 + 209*x^5 - 236*x^4 + 155*x^3 - 59*x^2 + 12*x - 1), {x, 0, 30}], x] (* Wesley Ivan Hurt, Aug 16 2015 *)
  • PARI
    Vec(-(5*x^6 - 3*x^5 - x^4 - x^3 + x^2)/(20*x^7 - 100*x^6 + 209*x^5 - 236*x^4 + 155*x^3 - 59*x^2 + 12*x - 1) + O(x^40)) \\ Michel Marcus, Aug 17 2015

Formula

G.f.: -x^2*(5*x^4-3*x^3-x^2-x+1)/((1-5*x+5*x^2)*(2*x-1)^2*(x-1)^3).
a(n) = 12*a(n-1) - 59*a(n-2) + 155*a(n-3) - 236*a(n-4) + 209*a(n-5) - 100*a(n-6) + 20*a(n-7). - Wesley Ivan Hurt, Jan 01 2024
a(n) = (n+2)*(n-1)/2-2^n*(1+3*n/2)+2*A030191(n)-5*A030191(n-1). - R. J. Mathar, Aug 26 2025