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 11-17 of 17 results.

A302913 Determinant of n X n matrix whose main diagonal consists of the first n 9-gonal numbers and all other elements are 1's.

Original entry on oeis.org

1, 8, 184, 8280, 612720, 67399200, 10312077600, 2093351752800, 544271455728000, 176343951655872000, 69655860904069440000, 32947222207624845120000, 18384549991854663576960000, 11949957494705531325024000000, 8950518163534442962442976000000
Offset: 1

Views

Author

Muniru A Asiru, Apr 15 2018

Keywords

Examples

			The matrix begins:
1   1   1   1   1   1   1 ...
1   9   1   1   1   1   1 ...
1   1  24   1   1   1   1 ...
1   1   1  46   1   1   1 ...
1   1   1   1  75   1   1 ...
1   1   1   1   1 111   1 ...
1   1   1   1   1   1 154 ...
		

Crossrefs

Cf. A001106 (nonagonal numbers).
Cf. Determinant of n X n matrix whose main diagonal consists of the first n k-gonal numbers and all other elements are 1's: A000142 (k=2), A067550 (k=3), A010791 (k=4, with offset 1), A302909 (k=5), A302910 (k=6), A302911 (k=7), A302912 (k=8), this sequence (k=9), A302914 (k=10).

Programs

  • Maple
    d:=(i,j)->`if`(i<>j,1,i*(7*i-5)/2):
    seq(LinearAlgebra[Determinant](Matrix(n,d)),n=1..16);
  • Mathematica
    nmax = 20; Table[Det[Table[If[i == j, i*(7*i-5)/2, 1], {i, 1, k}, {j, 1, k}]], {k, 1, nmax}] (* Vaclav Kotesovec, Apr 16 2018 *)
    RecurrenceTable[{a[n+1] == a[n] * n*(7*n + 9)/2, a[1] == 1}, a, {n, 1, 20}] (* Vaclav Kotesovec, Apr 16 2018 *)
    Table[FullSimplify[7^(n + 1) * Gamma[n] * Gamma[n + 9/7] / (9*Gamma[2/7]*2^n)], {n, 1, 15}] (* Vaclav Kotesovec, Apr 16 2018 *)
  • PARI
    a(n) = matdet(matrix(n, n, i, j, if (i!=j, 1, i*(7*i-5)/2))); \\ Michel Marcus, Apr 16 2018

Formula

From Vaclav Kotesovec, Apr 16 2018: (Start)
a(n) = 7^(n+1) * Gamma(n) * Gamma(n + 9/7) / (9 * Gamma(2/7) * 2^n).
a(n) ~ Pi * 7^(n+1) * n^(2*n + 2/7) / (9 * Gamma(2/7) * 2^(n-1) * exp(2*n)).
a(n+1) = a(n) * n*(7*n + 9)/2.
(End)

A302914 Determinant of n X n matrix whose main diagonal consists of the first n 10-gonal numbers and all other elements are 1's.

Original entry on oeis.org

1, 9, 234, 11934, 1002456, 125307000, 21803418000, 5036589558000, 1490830509168000, 550116457882992000, 247552406047346400000, 133430746859519709600000, 84861955002654535305600000, 62882708656967010661449600000, 53701833193049827104877958400000
Offset: 1

Views

Author

Muniru A Asiru, Apr 15 2018

Keywords

Comments

From Vaclav Kotesovec, Apr 16 2018: (Start)
In general, for k > 2, these determinants for k-gonal numbers satisfies:
a(n,k) = ((k-2)/2)^(n-1) * Gamma(n) * Gamma(n + k/(k-2)) / Gamma(1 + k/(k-2)).
a(n,k) ~ 4*Pi * (k/2 - 1)^n * n^(2*n + 2/(k-2)) / (k * Gamma(k/(k-2)) * exp(2*n)).
a(n+1,k) = a(n,k) * n*((k-2)*n + k)/2.
(End)

Examples

			The matrix begins:
  1   1   1   1   1   1   1 ...
  1  10   1   1   1   1   1 ...
  1   1  27   1   1   1   1 ...
  1   1   1  52   1   1   1 ...
  1   1   1   1  85   1   1 ...
  1   1   1   1   1 126   1 ...
  1   1   1   1   1   1 175 ...
		

Crossrefs

Cf. A001107.
Cf. Determinant of n X n matrix whose main diagonal consists of the first n k-gonal numbers and all other elements are 1's: A000142 (k=2), A067550 (k=3), A010791 (k=4, with offset 1), A302909 (k=5), A302910 (k=6), A302911 (k=7), A302912 (k=8), A302913 (k=9), this sequence (k=10).
Cf. A007840 (permanent instead of determinant, for k=2).

Programs

  • Maple
    d:=(i,j)->`if`(i<>j,1,i*(4*i-3)):
    seq(LinearAlgebra[Determinant](Matrix(n,d)),n=1..16);
  • Mathematica
    nmax = 20; Table[Det[Table[If[i == j, i*(4*i-3), 1], {i, 1, k}, {j, 1, k}]], {k, 1, nmax}] (* Vaclav Kotesovec, Apr 16 2018 *)
    RecurrenceTable[{a[n+1] == a[n] * n*(4*n + 5), a[1] == 1}, a, {n, 1, 20}] (* Vaclav Kotesovec, Apr 16 2018 *)
    Table[FullSimplify[4^(n+1) * Gamma[n] * Gamma[n + 5/4] / (5*Gamma[1/4])], {n, 1, 15}] (* Vaclav Kotesovec, Apr 16 2018 *)
  • PARI
    a(n) = matdet(matrix(n, n, i, j, if (i!=j, 1, i*(4*i-3)))); \\ Michel Marcus, Apr 16 2018

Formula

From Vaclav Kotesovec, Apr 16 2018: (Start)
a(n) = 4^(n+1) * Gamma(n) * Gamma(n + 5/4) / (5*Gamma(1/4)).
a(n) ~ Pi * 2^(2*n + 3) * n^(2*n + 1/4) / (5 * Gamma(1/4) * exp(2*n)).
a(n+1) = a(n) * n*(4*n + 5).
(End)

A158620 Partial products of A068601.

Original entry on oeis.org

7, 182, 11466, 1421784, 305683560, 104543777520, 53421870312720, 38891121587660160, 38852230466072499840, 51673466519876424787200, 89240076679826585607494400, 195971208388899181994057702400
Offset: 2

Views

Author

Jonathan Vos Post, Mar 23 2009

Keywords

Comments

A158621(n) = Product_{k=2..n} (k^3+1). A158622(n) is the numerator of the reduced fraction A158620(n)/A158621(n). A158623(n) is the denominator of the reduced fraction A158620(n)/A158621(n).
Also the determinant of the n X n matrix given by m(i,j) = i^3 if i=j and 1 otherwise. For example, Det[{{1,1,1, 1},{1,8,1,1},{1,1,27,1},{1,1,1,64}}] = 11466 = a(4). - John M. Campbell, May 20 2011

Examples

			a(2) = 2^3-1 = 7.
a(3) = (2^3-1)*(3^3-1) = 7 * 26 = 182.
a(4) = (2^3-1)*(3^3-1)*(4^3-1) = 7 * 26 * 63 = 11466.
		

Crossrefs

Programs

  • Mathematica
    Rest[FoldList[Times,1,Range[2,15]^3-1]] (* Harvey P. Dale, Apr 18 2015 *)
  • PARI
    a(n) = prod(k = 2, n, k^3 - 1); \\ Michel Marcus, Sep 29 2013

Formula

Product_{k=2..n} (k^3-1) = Product_{k=2..n} A068601(k).
a(n) ~ 2^(3/2) * sqrt(Pi) * cosh(sqrt(3)*Pi/2) * n^(3*n+3/2) / (3 * exp(3*n)). - Vaclav Kotesovec, Jul 11 2015

A303000 a(n) = permanent of the n X n matrix with entries a(i, i) = i^2 and a(i, j) = 1 elsewhere.

Original entry on oeis.org

1, 5, 52, 918, 24630, 934938, 47736048, 3157054776, 262661665176, 26857133054424, 3311299323349920, 484541686800059760, 83031688670103506160, 16472545369548670950480, 3746065113561656467249920, 968109978211279792380074880, 282158259444905145777416119680
Offset: 1

Views

Author

Vaclav Kotesovec, Apr 17 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Permanent[DiagonalMatrix[Table[i^2-1, {i, 1, n}]] + 1], {n, 1, 20}]
  • PARI
    {a(n) = matpermanent(matrix(n, n, i, j, if(i==j, i^2, 1)))}
    for(n=1, 20, print1(a(n), ", ")) \\ Vaclav Kotesovec, Dec 20 2018

A303001 a(n) = permanent of the n X n matrix with entries a(i, i) = i*(i+1)/2 and a(i, j) = 1 elsewhere.

Original entry on oeis.org

1, 4, 30, 356, 6106, 142760, 4363848, 168986136, 8087082144, 468807362736, 32379640476000, 2627735592279600, 247610398718738640, 26815386224063189760, 3307855985755600598400, 461149884030679844958720, 72151124506962747825006720, 12590610689213961622942752000
Offset: 1

Views

Author

Vaclav Kotesovec, Apr 17 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Permanent[DiagonalMatrix[Table[i*(i+1)/2-1, {i, 1, n}]] + 1], {n, 1, 20}]
  • PARI
    {a(n) = matpermanent(matrix(n, n, i, j, if(i==j, i*(i+1)/2, 1)))}
    for(n=1, 20, print1(a(n), ", ")) \\ Vaclav Kotesovec, Dec 20 2018

A064633 a(n) = 3^n*n!*(n+2)!/2!.

Original entry on oeis.org

1, 9, 216, 9720, 699840, 73483200, 10581580800, 1999918771200, 479980505088000, 142554210011136000, 51319515604008960000, 22016072194119843840000, 11096100385836401295360000, 6491218725714294757785600000, 4362098983680006077231923200000
Offset: 0

Views

Author

Karol A. Penson, Oct 01 2001

Keywords

Crossrefs

Programs

  • Mathematica
    Table[3^n n! (n+2)!/2,{n,0,20}] (* Harvey P. Dale, Feb 25 2015 *)
  • PARI
    { for (n=0, 75, write("b064633.txt", n, " ", 3^n*n!*(n + 2)!/2) ) } \\ Harry J. Smith, Sep 20 2009

Formula

Hypergeometric g.f.: (1-3*x)^(-3).
a(0)=1, a(n) = n!*subs(x=0, (d^n/dx^n)(-1/((3*x-1)^3))), n = 1, 2, ...
From Amiram Eldar, Sep 27 2022: (Start)
Sum_{n>=0} 1/a(n) = 6*BesselI(2,2/sqrt(3)).
Sum_{n>=0} (-1)^n/a(n) = 6*BesselJ(2,2/sqrt(3)). (End)

A319900 a(n) is the number of distinct ways to arrange n copies of each of the numbers 1 through n^2 inside a fixed n X n X n cube, provided that no number appears twice in the same left-right plane, front-back plane, or top-bottom plane.

Original entry on oeis.org

1, 24, 14515200, 7708721243457872461824000
Offset: 1

Views

Author

Tanya Khovanova and Wayne Zhao, Sep 30 2018

Keywords

Comments

When n = 3, this is equivalent to enumerating the different fill-ins of a Sudo-Kurve puzzle of the shape given in the link 'Sudo-Kurve 38'.

Examples

			For n = 2, the top layer of the 2 X 2 X 2 cube must contain each of the numbers 1, 2, 3, 4. This can be arranged in 24 ways. Each way uniquely determines the rest of the cube, so there are 24 possible cubes.
		

Crossrefs

Formula

Observation: a(n) = A010791(n*(n-1)) for 1 <= n <= 3. - Omar E. Pol, Oct 02 2018

Extensions

a(4) from Bert Dobbelaere, Sep 20 2019
Previous Showing 11-17 of 17 results.