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.

A296602 Values of F for which there is a unique convex polyhedron with F faces that are all regular polygons.

Original entry on oeis.org

4, 19, 23, 25, 29, 31, 33, 35, 39, 41, 43, 45, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 153, 155, 157, 159, 161, 163, 165, 167, 169, 171, 173
Offset: 1

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Author

Jonathan Sondow, Jan 28 2018

Keywords

Comments

The main entry for this sequence is A180916.
All terms except 4 are odd, because both the cube and the pentagonal pyramid have 6 faces, and for any even F > 6 both a prism and an antiprism can have F faces. Platonic solids, Archimedean solids, Johnson solids, and prisms account for the missing odd numbers.

Examples

			The regular tetrahedron is the only convex polyhedron with 4 faces that are all regular polygons, and no such polyhedron with fewer than 4 faces exists, so a(1) = 4.
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{2, -1}, {4, 19, 23, 25, 29, 31, 33, 35, 39, 41, 43, 45, 49, 51}, 30] (* Georg Fischer, Oct 26 2020 *)

Formula

A180916(a(n)) = 1.
From Colin Barker, Jul 05 2020: (Start)
G.f.: x*(4 + 11*x - 11*x^2 - 2*x^3 + 2*x^4 - 2*x^5 + 2*x^8 - 2*x^9 + 2*x^12 - 2*x^13) / (1 - x)^2.
a(n) = 2*a(n-1) - a(n-2) for n>14.
(End)

A333657 a(n) is the number of convex polyhedra whose faces are regular polygons and whose largest face is an n-gon.

Original entry on oeis.org

0, 0, 8, 30, 37, 14, 2, 9, 2, 22, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2
Offset: 1

Views

Author

Peter Kagey, Sep 02 2020

Keywords

Examples

			For n = 3, the a(3) = 8 polyhedra consisting of only equilateral triangles are: the tetrahedron, the octahedron, the icosahedron, and the Johnson solids J_12, J_13, J_17, J_51, and J_84.
For n = 8, the a(8) = 9 polyhedra containing an octagonal face but no face with more than eight sides are: the truncated cube, the truncated cuboctahedron, the octagonal prism, the octagonal antiprism, and the Johnson solids J_4, J_19, J_23, J_66, and J_67.
For n > 10, the a(n) = 2 polyhedra are the n-gonal prism and the n-gonal antiprism.
		

Crossrefs

Programs

  • Mathematica
    MaxFace[l_] := Max[Length /@ l];
    a[n_] := Count[
      Join[
        MaxFace /@ PolyhedronData["Platonic", "FaceIndices"],
        MaxFace /@ PolyhedronData["Archimedean", "FaceIndices"],
        MaxFace /@ PolyhedronData["Johnson", "FaceIndices"],
        Range[4, n], (*Prisms, including triangular prism, excluding cube*)
        Range[4, n]  (*Antiprisms, excluding octahedron*)
      ],
      n
    ]

A181708 Numbers of faces of polyhedra made entirely of regular polygons that are not prisms or antiprisms.

Original entry on oeis.org

4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 24, 26, 27, 30, 32, 34, 37, 38, 42, 47, 52, 62, 92
Offset: 1

Views

Author

J. Lowell, Nov 06 2010

Keywords

Comments

The prisms and antiprisms form infinite sequences of polyhedra that contain all integers >= 5 and all even numbers >= 8 respectively.

Examples

			19 is not in this sequence because the heptadecagonal prism is the only 19-faced polyhedron made entirely of regular polygons. 36 is not in this sequence because the 34-gonal prism and heptadecagonal antiprism are the only 36-faced polyhedra made entirely of regular polygons.
		

Crossrefs

A333660 a(n) is the number of n-vertex convex polyhedra whose faces are regular polygons.

Original entry on oeis.org

0, 0, 0, 1, 2, 3, 3, 6, 5, 7, 4, 10, 1, 6, 5, 6, 0, 6, 0, 8, 1, 4, 1, 8, 4, 2, 0, 3, 0, 9, 0, 3, 0, 2, 3, 2, 0, 2, 0, 5, 0, 2, 0, 2, 1, 2, 0, 3, 0, 5, 0, 2, 0, 2, 4, 2, 0, 2, 0, 10, 0, 2, 0, 2, 1, 2, 0, 2, 0, 4, 0, 2, 0, 2, 1, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2
Offset: 1

Views

Author

Peter Kagey, Sep 02 2020

Keywords

Comments

Convex polyhedra with whose faces are regular polygons are either Platonic solids, Archimedean solids, prisms, antiprisms, or Johnson solids.
For n > 120, there are two such convex polyhedra for even n, the (n/2)-gonal prism and (n/2)-gonal antiprism, and no polyhedra for odd n.

Examples

			For n = 12, the a(12) = 10 convex polyhedra with regular polygonal faces and 12 vertices are: the icosahedron, the truncated tetrahedron, the cuboctahedron, the hexagonal prism, the hexagonal antiprism, and the Johnson solids J_4, J_16, J_27, J_53, and J_88.
		

Crossrefs

Cf. A180916 (analog for faces), A333661 (analog for edges), A333657.

Programs

  • Mathematica
    a[n_] := Count[
      Join[
        PolyhedronData["Platonic", "VertexCount"],
        PolyhedronData["Archimedean", "VertexCount"],
        PolyhedronData["Johnson", "VertexCount"],
        Prepend[Range[10, n, 2], 6], (*Prisms, excluding cube*)
        Range[8, n, 2] (*Antiprisms, excluding octahedron*)
      ],
      n
    ]

A333661 a(n) is the number of convex polyhedra with n edges whose faces are regular polygons.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 1, 2, 1, 0, 3, 1, 1, 5, 2, 1, 4, 1, 6, 2, 2, 1, 5, 3, 4, 3, 2, 0, 4, 0, 3, 3, 0, 2, 8, 0, 1, 1, 6, 0, 2, 0, 2, 3, 0, 0, 5, 0, 2, 1, 1, 0, 1, 2, 2, 1, 0, 0, 8, 0, 0, 1, 1, 1, 1, 0, 1, 1, 3, 0, 3, 0, 0, 2, 1, 0, 1, 0, 4, 1, 0, 0, 2, 0, 0, 1
Offset: 1

Views

Author

Peter Kagey, Sep 02 2020

Keywords

Comments

Convex polyhedra with whose faces are regular polygons are either Platonic solids, Archimedean solids, prisms, antiprisms, or Johnson solids.

Examples

			For n = 18, the a(18) = 4 polyhedra are: the truncated tetrahedron, the hexagonal prism, and the Johnson solids J_64 and J_84.
For n > 180, the only polyhedra are the prisms and antiprisms. When 3 divides n, there is an (n/3)-gonal prism; when 4 divides n, and there is an (n/4)-gonal antiprism.
Starting at n = 181 the sequence has a 12-term cycle that goes 0,0,1,1,0,1,0,1,1,0,0,2. - _J. Lowell_, Oct 18 2020
		

Crossrefs

Cf. A180916 (analog for faces), A333660 (analog for vertices), A333657.

Programs

  • Mathematica
    a[n_] := Count[
      Join[
       PolyhedronData["Johnson", "EdgeCount"],
       PolyhedronData["Platonic", "EdgeCount"],
       PolyhedronData["Archimedean", "EdgeCount"],
       Prepend[Range[15, n, 3], 9], (*Prisms, excluding cube*)
       Range[16, n, 4] (*Antiprisms, excluding octahedron*)
      ],
      n
    ]
Showing 1-5 of 5 results.