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.

Previous Showing 11-16 of 16 results.

A326476 A(n, k) = (m*k)! [x^k] MittagLefflerE(m, x)^n, for m = 2, n >= 0, k >= 0; square array read by descending antidiagonals.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 8, 3, 1, 0, 1, 32, 21, 4, 1, 0, 1, 128, 183, 40, 5, 1, 0, 1, 512, 1641, 544, 65, 6, 1, 0, 1, 2048, 14763, 8320, 1205, 96, 7, 1, 0, 1, 8192, 132861, 131584, 26465, 2256, 133, 8, 1, 0, 1, 32768, 1195743, 2099200, 628805, 64896, 3787, 176, 9, 1
Offset: 0

Views

Author

Peter Luschny, Jul 08 2019

Keywords

Examples

			Array starts:
  [0] 1, 0,   0,    0,      0,        0,          0,            0, ... A000007
  [1] 1, 1,   1,    1,      1,        1,          1,            1, ... A000012
  [2] 1, 2,   8,   32,    128,      512,       2048,         8192, ... A081294
  [3] 1, 3,  21,  183,   1641,    14763,     132861,      1195743, ... A054879
  [4] 1, 4,  40,  544,   8320,   131584,    2099200,     33562624, ... A092812
  [5] 1, 5,  65, 1205,  26465,   628805,   15424865,    382964405, ... A121822
  [6] 1, 6,  96, 2256,  64896,  2086656,   71172096,   2499219456, ...
  [7] 1, 7, 133, 3787, 134953,  5501167,  243147373,  11266376947, ...
  [8] 1, 8, 176, 5888, 250496, 12397568,  676591616,  39316226048, ...
  [9] 1, 9, 225, 8649, 427905, 24943689, 1624354785, 114066126729, ...
        A000567,
Seen as a triangle:
  1;
  0, 1;
  0, 1,    1;
  0, 1,    2,      1;
  0, 1,    8,      3,      1;
  0, 1,   32,     21,      4,     1;
  0, 1,  128,    183,     40,     5,    1;
  0, 1,  512,   1641,    544,    65,    6,   1;
  0, 1, 2048,  14763,   8320,  1205,   96,   7, 1;
  0, 1, 8192, 132861, 131584, 26465, 2256, 133, 8, 1;
		

Crossrefs

Rows n=0..5 give A000007, A000012, A081294, A054879, A092812, A121822.
Columns include: A000567.
Main diagonal gives A381459.
Variant: A286899.
Cf. A326474 (m=3, p>=0), A326475 (m=3, p<=0), A326327 (m=2, p<=0), this sequence (m=2, p>=0).

Programs

  • Mathematica
    (* The function MLPower is defined in A326327. *)
    For[n = 0, n < 8, n++, Print[MLPower[2, n, 8]]]
  • PARI
    a(n, k) = (2*k)!*polcoef(cosh(x+x*O(x^(2*k)))^n, 2*k); \\ Seiichi Manyama, May 11 2025
  • Sage
    # uses[MLPower from A326327]
    for n in (0..6): print(MLPower(2, n, 9))
    

Formula

A(n,k) = (2*k)! * [x^(2*k)] cosh(x)^n. - Seiichi Manyama, May 11 2025

A328778 Number of indecomposable closed walks of length 2n along the edges of a cube based at a vertex.

Original entry on oeis.org

1, 3, 12, 84, 588, 4116, 28812, 201684, 1411788, 9882516, 69177612, 484243284, 3389702988, 23727920916, 166095446412, 1162668124884, 8138676874188, 56970738119316, 398795166835212, 2791566167846484, 19540963174925388
Offset: 0

Views

Author

Geoffrey Critzer, Oct 27 2019

Keywords

Comments

An indecomposable closed walk returns to its starting vertex exactly once (on the final step).
For n > 1, a(n) is the number of 4-colorings of the grid graph P_2 X P_(n-1). More generally, for q > 1, the number of q-colorings of the grid graph P_2 X P_n is given by q*(q - 1)*((q - 1)*(q - 2) + 1)^(n - 1). - Sela Fried, Sep 25 2023

Crossrefs

Programs

  • Mathematica
    nn = 40; list = Range[0, nn]! CoefficientList[Series[ Cosh[x]^3, {x, 0, nn}], x]; a = Sum[list[[i]] x^(i - 1), {i, 1, nn + 1}]; Select[CoefficientList[Series[ 2 - 1/a, {x, 0, nn}], x], # > 0 &]
  • PARI
    Vec((1 - 4*x - 9*x^2) / (1 - 7*x) + O(x^25)) \\ Colin Barker, Oct 28 2019

Formula

G.f.: 2 - 1/f(x) where f(x) is the g.f. for A054879.
From Colin Barker, Oct 27 2019: (Start)
G.f.: (1 - 4*x - 9*x^2) / (1 - 7*x).
a(n) = 7*a(n-1) for n>2.
a(n) = 12*7^(n - 2) for n>1.
(End)
E.g.f.: (1/49)*(37 + 12*exp(7*x) + 63*x). - Stefano Spezia, Oct 27 2019

A158303 Triangle read by rows, A007318 * (A158300 * 0^(n-k)).

Original entry on oeis.org

1, 1, 2, 1, 4, 2, 1, 6, 6, 8, 1, 8, 12, 32, 8, 1, 10, 20, 80, 40, 32, 1, 12, 30, 160, 120, 192, 32, 1, 14, 42, 280, 280, 672, 224, 128, 1, 16, 56, 448, 560, 1792, 896, 1024, 128, 1, 18, 72, 672, 1008, 4032, 2688, 4608, 1152, 512
Offset: 0

Views

Author

Gary W. Adamson, Mar 15 2009

Keywords

Examples

			First few rows of the triangle =
1;
1, 2;
1, 4, 2;
1, 6, 6, 8;
1, 8, 12, 32, 8;
1, 10, 20, 80, 40, 32;
1, 12, 30, 160, 120, 192, 32;
1, 14, 42, 280, 280, 672, 224, 128;
1, 16, 56, 448, 560, 1792, 896, 1024, 128;
1, 18, 72, 672, 1008, 4032, 2688, 4608, 1152, 512;
1, 20, 90, 960, 1680, 8064, 6720, 15360, 5760, 5120, 512;
...
		

Crossrefs

Cf. A158300, A122983 (row sums), A054879, A066443

Formula

Triangle read by rows, A007318 * (A158300 * 0^(n-k)). Equals binomial transform of an infinite lower triangular matrix with A158300: (1, 2, 2, 8, 8, 32, 32,...) as the main diagonal and the rest zeros.

A328821 Triangular array read by rows. Let P be the poset of all even sized subsets of [2n] ordered by inclusion. T(n,k) is the number of intervals in P with length k, 0<=k<=n, n>=0.

Original entry on oeis.org

1, 2, 1, 8, 12, 1, 32, 120, 30, 1, 128, 896, 560, 56, 1, 512, 5760, 6720, 1680, 90, 1, 2048, 33792, 63360, 29568, 3960, 132, 1, 8192, 186368, 512512, 384384, 96096, 8008, 182, 1, 32768, 983040, 3727360, 4100096, 1647360, 256256, 14560, 240, 1
Offset: 0

Views

Author

Geoffrey Critzer, Jun 07 2020

Keywords

Examples

			1,
2,   1,
8,   12,   1,
32,  120,  30,   1,
128, 896,  560,  56,   1,
512, 5760, 6720, 1680, 90, 1
		

Crossrefs

Cf. A054879 (row sums), A081294 (column k=0).

Programs

  • Mathematica
    nn = 8; ev[x_] := Sum[x^n/((2 n)!/2^n), {n, 0, nn}];
    Map[Select[#, # > 0 &] &, Table[(2 n)!/2^n, {n, 0, nn}] CoefficientList[Series[ev[x]^2 ev[y x], {x, 0, nn}], {x, y}]] // Flatten

Formula

Let E(x) = Sum_{n>=0} x^n/((2n)!/2^n). Then Sum_{n>=0} Sum{k=0..n} T(n,k) y^k*x^n/((2n)!/2^n) = E(y*x) * E(x)^2.

A336667 Triangular array read by rows. T(n,k) is the number of closed walks of length 2n along the edges of a cube based at vertex v that return to v exactly k times, n>=0, 0<=k<=n.

Original entry on oeis.org

1, 0, 3, 0, 12, 9, 0, 84, 72, 27, 0, 588, 648, 324, 81, 0, 4116, 5544, 3564, 1296, 243, 0, 28812, 45864, 35748, 16848, 4860, 729, 0, 201684, 370440, 337932, 193104, 72900, 17496, 2187
Offset: 0

Views

Author

Geoffrey Critzer, Jul 29 2020

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  0,   3;
  0,  12,   9;
  0,  84,  72,  27;
  0, 588, 648, 324, 81;
  ...
		

Crossrefs

Cf. A054879 (row sums), A328778 (column k=1).

Programs

  • Mathematica
    Table[nn = n; CoefficientList[Series[(1 - 7 z^2)/(1 - (7 + 3 u) z^2 + 9 u z^4), {z, 0, nn}], {z,u}][[-1]], {n, 0, 15, 2}] // Grid

Formula

O.g.f.: (1 - 7*x^2)/(1 - 7*x^2 - 3*y*x^2 + 9*y*x^4).

A377946 Cogrowth sequence of the 16-element group C2^2:C4 = .

Original entry on oeis.org

1, 1, 2, 10, 40, 136, 512, 2080, 8320, 32896, 131072, 524800, 2099200, 8390656, 33554432, 134225920, 536903680, 2147516416, 8589934592, 34359869440, 137439477760, 549756338176, 2199023255552, 8796095119360, 35184380477440, 140737496743936, 562949953421312
Offset: 0

Views

Author

Sean A. Irvine, Nov 11 2024

Keywords

Comments

Gives the even terms, all the odd terms are 0.
Also called K8:C2. Gap identifier 16, 3.

Crossrefs

Cf. A377855 (C4:C4), A054879 (C2^3), A377843 (C4 X C2^2), A377943 (C4 o D4).

Formula

G.f.: (12*x^4-14*x^3+8*x^2-5*x+1) / ((4*x-1) * (2*x-1) * (4*x^2+1)).
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