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 1-8 of 8 results.

A333513 Square array T(n,k), n >= 2, k >= 2, read by antidiagonals, where T(n,k) is the number of self-avoiding closed paths on an n X k grid which pass through four corners ((0,0), (0,k-1), (n-1,k-1), (n-1,0)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 3, 1, 1, 7, 11, 7, 1, 1, 17, 49, 49, 17, 1, 1, 41, 229, 373, 229, 41, 1, 1, 99, 1081, 3105, 3105, 1081, 99, 1, 1, 239, 5123, 26515, 44930, 26515, 5123, 239, 1, 1, 577, 24323, 227441, 674292, 674292, 227441, 24323, 577, 1
Offset: 2

Views

Author

Seiichi Manyama, Mar 25 2020

Keywords

Examples

			Square array T(n,k) begins:
  1,  1,    1,     1,      1,        1, ...
  1,  1,    3,     7,     17,       41, ...
  1,  3,   11,    49,    229,     1081, ...
  1,  7,   49,   373,   3105,    26515, ...
  1, 17,  229,  3105,  44930,   674292, ...
  1, 41, 1081, 26515, 674292, 17720400, ...
		

Crossrefs

Column k=2-7 give: A000012, A001333(n-2), A333514, A333515, A358712, A358713.
Main diagonal gives A333466.
Cf. A333758.

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    import graphillion.tutorial as tl
    def A333513(n, k):
        universe = tl.grid(n - 1, k - 1)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles()
        for i in [1, k, k * (n - 1) + 1, k * n]:
            cycles = cycles.including(i)
        return cycles.len()
    print([A333513(j + 2, i - j + 2) for i in range(11 - 1) for j in range(i + 1)])

Formula

T(n,k) = T(k,n).

A333246 Number of self-avoiding closed paths on an n X n grid which pass through NW corner.

Original entry on oeis.org

1, 7, 97, 4111, 532269, 212372937, 263708907211, 1013068026356375, 11955420069208095719, 432101605951906251627393, 47778407166747833830058004149, 16149888968763663448192636077980753, 16675786862526496319891707194153887550751, 52568166380872328447478940416604864445574575709
Offset: 2

Views

Author

Seiichi Manyama, Mar 23 2020

Keywords

Examples

			a(2) = 1;
   +--*
   |  |
   *--*
a(3) = 7;
   +--*      +--*--*   +--*--*   +--*
   |  |      |     |   |     |   |  |
   *--*      *--*--*   *     *   *  *
                       |     |   |  |
                       *--*--*   *--*
   +--*--*   +--*--*   +--*
   |     |   |     |   |  |
   *  *--*   *--*  *   *  *--*
   |  |         |  |   |     |
   *--*         *--*   *--*--*
		

Crossrefs

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    import graphillion.tutorial as tl
    def A333246(n):
        universe = tl.grid(n - 1, n - 1)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles().including(1)
        return cycles.len()
    print([A333246(n) for n in range(2, 10)])

Formula

a(n) = A333439(n) - 1 for n > 1.

Extensions

a(11), a(13) from Seiichi Manyama, Apr 07 2020
a(10), a(12), a(14)-a(15) from Andrew Howroyd, Jan 30 2022

A333323 Number of self-avoiding closed paths on an n X n grid which pass through NW and SE corners.

Original entry on oeis.org

1, 3, 42, 1799, 232094, 92617031, 115156685746, 442641690778179, 5224287477491915786, 188825256606226776728029, 20879416139356164466643759334, 7057757437924198729598570424130207, 7287699030020917172151307665469211016474, 22973720258279267139936821063450448822110219653
Offset: 2

Views

Author

Seiichi Manyama, Mar 23 2020

Keywords

Examples

			a(2) = 1;
   +--*
   |  |
   *--+
a(3) = 3;
   +--*--*   +--*--*   +--*
   |     |   |     |   |  |
   *--*  *   *     *   *  *--*
      |  |   |     |   |     |
      *--+   *--*--+   *--*--+
		

Crossrefs

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    import graphillion.tutorial as tl
    def A333323(n):
        universe = tl.grid(n - 1, n - 1)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles().including(1).including(n * n)
        return cycles.len()
    print([A333323(n) for n in range(2, 10)])

Extensions

a(11) from Seiichi Manyama, Apr 07 2020
a(10) and a(12)-a(15) from Vaclav Kotesovec, Aug 16 2022 (computed by Anthony Guttmann)

A333247 Number of self-avoiding closed paths on an n X n grid which pass through NW and SW corners.

Original entry on oeis.org

1, 4, 47, 1843, 232905, 92729439, 115234959344, 442748883422394
Offset: 2

Views

Author

Seiichi Manyama, Mar 23 2020

Keywords

Comments

a(11) = 188829168009674568016545. - Seiichi Manyama, Apr 07 2020

Examples

			a(2) = 1;
   +--*
   |  |
   +--*
a(3) = 4;
   +--*--*   +--*--*   +--*      +--*
   |     |   |     |   |  |      |  |
   *     *   *  *--*   *  *--*   *  *
   |     |   |  |      |     |   |  |
   +--*--*   +--*      +--*--*   +--*
		

Crossrefs

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    import graphillion.tutorial as tl
    def A333247(n):
        universe = tl.grid(n - 1, n - 1)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles().including(1).including(n)
        return cycles.len()
    print([A333247(n) for n in range(2, 10)])

A333668 Triangle T(n,k), n >= 2, 0 <= k <= floor(n^2/2)-2*n+2, read by rows, where T(n,k) is the number of 2*(k+2*n-2)-cycles in the n X n grid graph which pass through four corners ((0,0), (0,n-1), (n-1,n-1), (n-1,0)).

Original entry on oeis.org

1, 1, 1, 4, 6, 1, 12, 58, 156, 146, 1, 24, 244, 1416, 5435, 12976, 16654, 7108, 1072, 1, 40, 696, 7076, 47965, 236628, 873610, 2348664, 4335724, 4958224, 3407276, 1298704, 205792
Offset: 2

Views

Author

Seiichi Manyama, Apr 01 2020

Keywords

Examples

			T(4,1) = 4;
   +--*--*--+   +--*--*--+   +--*--*--+   +--*  *--+
   |        |   |        |   |        |   |  |  |  |
   *--*     *   *     *--*   *        *   *  *--*  *
      |     |   |     |      |        |   |        |
   *--*     *   *     *--*   *  *--*  *   *        *
   |        |   |        |   |  |  |  |   |        |
   +--*--*--+   +--*--*--+   +--*  *--+   +--*--*--+
Triangle starts:
=================================================================
n\k| 0   1     2      3       4 ...       8 ...    12 ...     18
---|-------------------------------------------------------------
2  | 1;
3  | 1;
4  | 1,  4,    6;
5  | 1, 12,   58,   156,    146;
6  | 1, 24,  244,  1416,   5435, ... , 1072;
7  | 1, 40,  696,  7076,  47965, ........... , 205792;
8  | 1, 60, 1590, 24960, 263770, ..................... , 4638576;
		

Crossrefs

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    import graphillion.tutorial as tl
    def A333668(n):
        universe = tl.grid(n - 1, n - 1)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles()
        for i in [1, n, n * (n - 1) + 1, n * n]:
            cycles = cycles.including(i)
        return [cycles.len(2 * k).len() for k in range(2 * n - 2, n * n // 2 + 1)]
    print([i for n in range(2, 8) for i in A333668(n)])

Formula

T(n,0) = 1.
T(n,1) = A046092(n-3).

A333759 Number of self-avoiding closed paths in the n X n grid graph which pass through all vertices on four (left, right, upper, lower) sides of the graph.

Original entry on oeis.org

1, 1, 11, 191, 11346, 2002405, 1112939654, 1878223479450
Offset: 2

Views

Author

Seiichi Manyama, Apr 04 2020

Keywords

Comments

a(11) = 152567999801505122456.

Examples

			a(2) = 1;
   +--+
   |  |
   +--+
a(3) = 1;
   +--+--+
   |     |
   +     +
   |     |
   +--+--+
a(4) = 11;
   +--+--+--+   +--+--+--+   +--+--+--+
   |        |   |        |   |        |
   +--*--*  +   +--*  *--+   +--*     +
         |  |      |  |         |     |
   +--*--*  +   +--*  *--+   +--*     +
   |        |   |        |   |        |
   +--+--+--+   +--+--+--+   +--+--+--+
   +--+--+--+   +--+--+--+   +--+--+--+
   |        |   |        |   |        |
   +  *--*--+   +  *--*  +   +     *--+
   |  |         |  |  |  |   |     |
   +  *--*--+   +  *  *  +   +     *--+
   |        |   |  |  |  |   |        |
   +--+--+--+   +--+  +--+   +--+--+--+
   +--+--+--+   +--+--+--+   +--+  +--+
   |        |   |        |   |  |  |  |
   +        +   +        +   +  *--*  +
   |        |   |        |   |        |
   +  *--*  +   +        +   +  *--*  +
   |  |  |  |   |        |   |  |  |  |
   +--+  +--+   +--+--+--+   +--+  +--+
   +--+  +--+   +--+  +--+
   |  |  |  |   |  |  |  |
   +  *--*  +   +  *  *  +
   |        |   |  |  |  |
   +        +   +  *--*  +
   |        |   |        |
   +--+--+--+   +--+--+--+
		

Crossrefs

Main diagonal of A333758.
Cf. A333466.

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    import graphillion.tutorial as tl
    def A333759(n):
        universe = tl.grid(n - 1, n - 1)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles()
        points = [i for i in range(1, n * n + 1) if i % n < 2 or ((i - 1) // n + 1) % n < 2]
        for i in points:
            cycles = cycles.including(i)
        return cycles.len()
    print([A333759(n) for n in range(2, 10)])

A333795 Number of self-avoiding closed paths on an n X n grid which pass through all points on the two diagonals of the grid.

Original entry on oeis.org

1, 0, 6, 68, 6102, 1404416, 1094802826, 2524252113468
Offset: 2

Views

Author

Seiichi Manyama, Apr 05 2020

Keywords

Comments

a(11) = 407977071391342237828.

Examples

			a(2) = 1;
   +--+
   |  |
   +--+
a(4) = 6;
   +--*--*--+   +--*--*--+   +--*--*--+
   |        |   |        |   |        |
   *--+--+  *   *--+  +--*   *  +--+--*
         |  |      |  |      |  |
   *--+--+  *   *--+  +--*   *  +--+--*
   |        |   |        |   |        |
   +--*--*--+   +--*--*--+   +--*--*--+
   +--*--*--+   +--*  *--+   +--*  *--+
   |        |   |  |  |  |   |  |  |  |
   *  +--+  *   *  +--+  *   *  +  +  *
   |  |  |  |   |        |   |  |  |  |
   *  +  +  *   *  +--+  *   *  +--+  *
   |  |  |  |   |  |  |  |   |        |
   +--*  *--+   +--*  *--+   +--*--*--+
		

Crossrefs

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    import graphillion.tutorial as tl
    def A333795(n):
        universe = tl.grid(n - 1, n - 1)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles()
        points = [i + 1 for i in range(n * n) if i % n - i // n == 0 or i % n + i // n == n - 1]
        for i in points:
            cycles = cycles.including(i)
        return cycles.len()
    print([A333795(n) for n in range(2, 10)])

A333796 Number of self-avoiding closed paths on an n X n grid which pass through all points on the diagonal connecting NW and SE corners.

Original entry on oeis.org

1, 2, 22, 716, 73346, 23374544, 23037365786, 69630317879888
Offset: 2

Views

Author

Seiichi Manyama, Apr 05 2020

Keywords

Comments

a(11) = 18267559028025887599256.

Examples

			a(2) = 1;
   +--*
   |  |
   *--+
a(3) = 2;
   +--*--*   +--*
   |     |   |  |
   *--+  *   *  +--*
      |  |   |     |
      *--+   *--*--+
a(4) = 22;
   +--*--*--*   +--*--*--*   +--*--*--*
   |        |   |        |   |        |
   *--+--*  *   *--+--*  *   *--+--*  *
         |  |         |  |         |  |
   *--*--+  *      *--+  *         +  *
   |        |      |     |         |  |
   *--*--*--+      *--*--+         *--+
   +--*--*--*   +--*--*--*   +--*--*--*
   |        |   |        |   |        |
   *--+  *--*   *--+  *--*   *--+     *
      |  |         |  |         |     |
   *--*  +--*      *  +--*      *--+  *
   |        |      |     |         |  |
   *--*--*--+      *--*--+         *--+
   +--*--*--*   +--*--*--*   +--*--*--*
   |        |   |        |   |        |
   *  +--*--*   *  +--*  *   *  +--*  *
   |  |         |  |  |  |   |  |  |  |
   *  *--+--*   *--*  +  *   *  *  +  *
   |        |         |  |   |  |  |  |
   *--*--*--+         *--+   *--*  *--+
   +--*--*      +--*--*      +--*--*
   |     |      |     |      |     |
   *--+  *--*   *--+  *      *--+  *
      |     |      |  |         |  |
      *--+  *   *--*  +--*      *  +--*
         |  |   |        |      |     |
         *--+   *--*--*--+      *--*--+
   +--*--*      +--*  *--*   +--*  *--*
   |     |      |  |  |  |   |  |  |  |
   *  +--*      *  +--*  *   *  +--*  *
   |  |         |        |   |        |
   *  *--+--*   *--*--+  *   *  *--+  *
   |        |         |  |   |  |  |  |
   *--*--*--+         *--+   *--*  *--+
   +--*  *--*   +--*         +--*
   |  |  |  |   |  |         |  |
   *  +  *  *   *  +--*--*   *  +--*--*
   |  |  |  |   |        |   |        |
   *  *--+  *   *--*--+  *   *  *--+  *
   |        |         |  |   |  |  |  |
   *--*--*--+         *--+   *--*  *--+
   +--*         +--*         +--*
   |  |         |  |         |  |
   *  +--*      *  +--*      *  +  *--*
   |     |      |     |      |  |  |  |
   *--*  +--*   *     +--*   *  *--+  *
      |     |   |        |   |        |
      *--*--+   *--*--*--+   *--*--*--+
   +--*
   |  |
   *  +
   |  |
   *  *--+--*
   |        |
   *--*--*--+
		

Crossrefs

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    import graphillion.tutorial as tl
    def A333796(n):
        universe = tl.grid(n - 1, n - 1)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles()
        points = [i + 1 for i in range(n * n) if i % n - i // n == 0]
        for i in points:
            cycles = cycles.including(i)
        return cycles.len()
    print([A333796(n) for n in range(2, 10)])
Showing 1-8 of 8 results.