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.

Showing 1-2 of 2 results.

A298117 Array read by antidiagonals: T(m,n) = number of Eulerian cycles in the torus grid graph C_m X C_n.

Original entry on oeis.org

2, 4, 4, 8, 40, 8, 16, 320, 320, 16, 32, 2368, 8616, 2368, 32, 64, 16832, 207496, 207496, 16832, 64, 128, 116608, 4788808, 15639936, 4788808, 116608, 128, 256, 793088, 108326760, 1116199200, 1116199200, 108326760, 793088, 256
Offset: 1

Views

Author

Andrew Howroyd, Jan 12 2018

Keywords

Examples

			Array begins:
=========================================================================
m\n|  1      2         3           4              5                 6
---|---------------------------------------------------------------------
1  |  2      4         8          16             32                64 ...
2  |  4     40       320        2368          16832            116608 ...
3  |  8    320      8616      207496        4788808         108326760 ...
4  | 16   2368    207496    15639936     1116199200       77643032832 ...
5  | 32  16832   4788808  1116199200   242230440480    50917973008584 ...
6  | 64 116608 108326760 77643032832 50917973008584 32098460087825856 ...
...
		

Crossrefs

Rows 2..4 are A298198, A282621, A298197.
Main diagonal is A297385.

A298201 Number of Eulerian orientations of the torus grid graph C_4 X C_n.

Original entry on oeis.org

32, 114, 548, 2970, 16892, 98466, 583412, 3500970, 21232556, 129930354, 801132452, 4970993658, 31006439132, 194231313474, 1220944803668, 7696445791050, 48625129598732, 307759067766546, 1950657679387652, 12377791111168410, 78613025212107836, 499635602835227874
Offset: 1

Views

Author

Andrew Howroyd, Jan 14 2018

Keywords

Crossrefs

Row 4 of A298119.

Programs

  • Mathematica
    LinearRecurrence[{15, -77, 161, -138, 40}, {32, 114, 548, 2970, 16892}, 22] (* Jean-François Alcover, Sep 21 2019 *)
  • PARI
    Vec(2*(16 - 183*x + 651*x^2 - 812*x^3 + 300*x^4)/((1 - x)*(1 - 2*x)*(1 - 5*x)*(1 - 7*x + 4*x^2)) + O(x^25))

Formula

a(n) = 15*a(n-1) - 77*a(n-2) + 161*a(n-3) - 138*a(n-4) + 40*a(n-5).
G.f.: 2*x*(16 - 183*x + 651*x^2 - 812*x^3 + 300*x^4)/((1 - x)*(1 - 2*x)*(1 - 5*x)*(1 - 7*x + 4*x^2)).
Showing 1-2 of 2 results.