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 1-5 of 5 results.

A339075 Number of (undirected) cycles in the graph C_4 X C_n.

Original entry on oeis.org

1531, 14704, 132089, 1165194, 10254423, 90693764, 808627861, 7276584222, 66085185907, 605303076120, 5585690299505, 51868931553714, 484136128508431, 4537416076416428, 42662439747995981, 402124615161547590, 3797500862839734443, 35913373920441057600, 340000796575687888937
Offset: 3

Views

Author

Seiichi Manyama, Nov 22 2020

Keywords

Crossrefs

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    def make_CnXCk(n, k):
        grids = []
        for i in range(1, k + 1):
            for j in range(1, n):
                grids.append((i + (j - 1) * k, i + j * k))
            grids.append((i + (n - 1) * k, i))
        for i in range(1, k * n, k):
            for j in range(1, k):
                grids.append((i + j - 1, i + j))
            grids.append((i + k - 1, i))
        return grids
    def A339075(n):
        universe = make_CnXCk(4, n)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles()
        return cycles.len()
    print([A339075(n) for n in range(3, 30)])

A339136 Number of (undirected) cycles in the graph C_3 X P_n.

Original entry on oeis.org

1, 14, 63, 220, 701, 2154, 6523, 19640, 59001, 177094, 531383, 1594260, 4782901, 14348834, 43046643, 129140080, 387420401, 1162261374, 3486784303, 10460353100, 31381059501, 94143178714, 282429536363, 847288609320, 2541865828201, 7625597484854, 22876792454823, 68630377364740
Offset: 1

Views

Author

Seiichi Manyama, Nov 25 2020

Keywords

Crossrefs

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    def make_CnXPk(n, k):
        grids = []
        for i in range(1, k + 1):
            for j in range(1, n):
                grids.append((i + (j - 1) * k, i + j * k))
            grids.append((i + (n - 1) * k, i))
        for i in range(1, k * n, k):
            for j in range(1, k):
                grids.append((i + j - 1, i + j))
        return grids
    def A339136(n):
        universe = make_CnXPk(3, n)
        GraphSet.set_universe(universe)
        cycles = GraphSet.cycles()
        return cycles.len()
    print([A339136(n) for n in range(1, 20)])

Formula

Empirical g.f.: -x*(9*x+1) / ((x-1)^2 * (3*x-1)). - Vaclav Kotesovec, Dec 09 2020

A339795 Number of (undirected) paths in the graph C_3 X C_n.

Original entry on oeis.org

4536, 41676, 324570, 2298906, 15340836, 98401032, 614180286, 3759485910, 22684148388, 135385868268, 801141412422, 4708188092034, 27512477620020, 160001531341584, 926684449543278, 5347897587948078, 30765345147232932, 176489253686952180, 1009897820473377654
Offset: 3

Views

Author

Seiichi Manyama, Dec 17 2020

Keywords

Crossrefs

Cf. A339074, A339797 (Hamiltonian paths).

Programs

  • Python
    # Using graphillion
    from graphillion import GraphSet
    def make_CnXCk(n, k):
        grids = []
        for i in range(1, k + 1):
            for j in range(1, n):
                grids.append((i + (j - 1) * k, i + j * k))
            grids.append((i + (n - 1) * k, i))
        for i in range(1, k * n, k):
            for j in range(1, k):
                grids.append((i + j - 1, i + j))
            grids.append((i + k - 1, i))
        return grids
    def A(start, goal, n, k):
        universe = make_CnXCk(n, k)
        GraphSet.set_universe(universe)
        paths = GraphSet.paths(start, goal)
        return paths.len()
    def B(n, k):
        m = k * n
        s = 0
        for i in range(1, m):
            for j in range(i + 1, m + 1):
                s += A(i, j, n, k)
        return s
    def A339795(n):
        return B(n, 3)
    print([A339795(n) for n in range(3, 10)])

A358855 Number of (undirected) cycles in the graph C_5 X C_n.

Original entry on oeis.org

7298, 132089, 2183490, 34846271, 548520502, 8593998133, 134605124804, 2112734282875, 33277625395316, 526401223244097, 8365394600819118, 133560895142858179, 2142023381577621160, 34497747586243864061, 557716750350292506722, 9047143455744392381123
Offset: 3

Views

Author

Seiichi Manyama, Dec 03 2022

Keywords

Crossrefs

Extensions

a(9)-a(18) from Andrew Howroyd, Jan 28 2023

A358856 Number of (undirected) cycles in the graph C_6 X C_n.

Original entry on oeis.org

35205, 1165194, 34846271, 995818716, 27888940001, 773821636750, 21378607696815, 589724385779004, 16270311004670729, 449476421435825046, 12442365158796491483, 345293706994488530008, 9609116953522118190009, 268189777386676703675238, 7507073356371047897526119, 210735605847160867677182616
Offset: 3

Views

Author

Seiichi Manyama, Dec 03 2022

Keywords

Crossrefs

Extensions

a(7)-a(18) from Andrew Howroyd, Jan 28 2023
Showing 1-5 of 5 results.