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 1-7 of 7 results.

A337419 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of sqrt((1-(k+4)*x+sqrt(1+2*(k-4)*x+((k+4)*x)^2)) / (2 * (1+2*(k-4)*x+((k+4)*x)^2))).

Original entry on oeis.org

1, 1, 2, 1, 1, 6, 1, 0, -5, 20, 1, -1, -14, -41, 70, 1, -2, -21, -48, -125, 252, 1, -3, -26, -7, 198, 131, 924, 1, -4, -29, 76, 739, 2080, 3301, 3432, 1, -5, -30, 195, 1222, 1629, 1780, 15625, 12870, 1, -6, -29, 344, 1395, -3772, -26859, -57120, 16115, 48620
Offset: 0

Views

Author

Seiichi Manyama, Aug 27 2020

Keywords

Examples

			Square array begins:
    1,    1,    1,    1,     1,      1, ...
    2,    1,    0,   -1,    -2,     -3, ...
    6,   -5,  -14,  -21,   -26,    -29, ...
   20,  -41,  -48,   -7,    76,    195, ...
   70, -125,  198,  739,  1222,   1395, ...
  252,  131, 2080, 1629, -3772, -14873, ...
		

Crossrefs

Columns k=0..4 give A000984, A337393, A337421, A337422, A337396.
Main diagonal gives A337420.

Programs

  • Mathematica
    T[n_, k_] := Sum[If[k == 0, Boole[n == j], (-k)^(n - j)] * Binomial[2*j, j] * Binomial[2*n, 2*j], {j, 0, n}]; Table[T[k, n - k], {n, 0, 9}, {k, 0, n}] // Flatten (* Amiram Eldar, Aug 27 2020 *)
  • PARI
    {T(n, k) = sum(j=0, n, (-k)^(n-j)*binomial(2*j, j)*binomial(2*n, 2*j))}

Formula

T(n,k) = Sum_{j=0..n} (-k)^(n-j) * binomial(2*j,j) * binomial(2*n,2*j).
T(0,k) = 1, T(1,k) = 2-k and n * (2*n-1) * (4*n-5) * T(n,k) = (4*n-3) * (-4*(k-4)*n^2+6*(k-4)*n-k+6) * T(n-1,k) - (k+4)^2 * (n-1) * (2*n-3) * (4*n-1) * T(n-2,k) for n > 1. - Seiichi Manyama, Aug 28 2020

A337369 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of sqrt(2 / ( (1-2*(k+4)*x+((k-4)*x)^2) * (1+(k-4)*x+sqrt(1-2*(k+4)*x+((k-4)*x)^2)) )).

Original entry on oeis.org

1, 1, 6, 1, 7, 30, 1, 8, 51, 140, 1, 9, 74, 393, 630, 1, 10, 99, 736, 3139, 2772, 1, 11, 126, 1175, 7606, 25653, 12012, 1, 12, 155, 1716, 14499, 80464, 212941, 51480, 1, 13, 186, 2365, 24310, 183195, 864772, 1787607, 218790, 1, 14, 219, 3128, 37555, 352716, 2351805, 9400192, 15134931, 923780
Offset: 0

Views

Author

Seiichi Manyama, Aug 25 2020

Keywords

Examples

			Square array begins:
     1,     1,     1,      1,      1,      1, ...
     6,     7,     8,      9,     10,     11, ...
    30,    51,    74,     99,    126,    155, ...
   140,   393,   736,   1175,   1716,   2365, ...
   630,  3139,  7606,  14499,  24310,  37555, ...
  2772, 25653, 80464, 183195, 352716, 610897, ...
		

Crossrefs

Columns k=0..5 give A002457, A273055, A337370, A245927, A002458, A243947.
Main diagonal gives A337387.

Programs

  • Mathematica
    T[n_, k_] := Sum[If[k == 0, Boole[n == j], k^(n - j)] * Binomial[2*j, j] * Binomial[2*n + 1, 2*j], {j, 0, n}]; Table[T[k, n - k], {n, 0, 9}, {k, 0, n}] // Flatten (* Amiram Eldar, Aug 25 2020 *)
  • PARI
    {T(n, k) = sum(j=0, n, k^(n-j)*binomial(2*j, j)*binomial(2*n+1, 2*j))}

Formula

T(n,k) = Sum_{j=0..n} k^(n-j) * binomial(2*j,j) * binomial(2*n+1,2*j).
T(0,k) = 1, T(1,k) = k+6 and n * (2*n+1) * (4*n-3) * T(n,k) = (4*n-1) * (4*(k+4)*n^2-2*(k+4)*n-k-2) * T(n-1,k) - (k-4)^2 * (n-1) * (2*n-1) * (4*n+1) * T(n-2,k) for n > 1. - Seiichi Manyama, Aug 29 2020
For fixed k > 0, T(n,k) ~ (2 + sqrt(k))^(2*n + 3/2) / sqrt(8*k*Pi*n). - Vaclav Kotesovec, Aug 31 2020

A337394 Expansion of sqrt(2 / ( (1-6*x+25*x^2) * (1-5*x+sqrt(1-6*x+25*x^2)) )).

Original entry on oeis.org

1, 5, 11, -29, -365, -1409, -155, 29485, 170035, 309775, -2064655, -18909175, -61552739, 81290561, 1901796395, 9145986419, 8604744275, -165227713249, -1168032362879, -2913302013175, 10702975797545, 132134872338925, 519716440255535, -109051949915065, -13098011769247075
Offset: 0

Views

Author

Seiichi Manyama, Aug 25 2020

Keywords

Crossrefs

Column k=1 of A337464.

Programs

  • Mathematica
    a[n_] := Sum[(-1)^(n-k) * Binomial[2*k, k] * Binomial[2*n+1, 2*k], {k, 0, n}]; Array[a, 25, 0] (* Amiram Eldar, Apr 29 2021 *)
  • PARI
    N=40; x='x+O('x^N); Vec(sqrt(2/((1-6*x+25*x^2)*(1-5*x+sqrt(1-6*x+25*x^2)))))
    
  • PARI
    {a(n) = sum(k=0, n, (-1)^(n-k)*binomial(2*k, k)*binomial(2*n+1, 2*k))}

Formula

a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(2*k,k) * binomial(2*n+1,2*k).
a(0) = 1, a(1) = 5 and n * (2*n+1) * (4*n-3) * a(n) = (4*n-1) * (12*n^2-6*n-1) * a(n-1) - 25 * (n-1) * (2*n-1) * (4*n+1) * a(n-2) for n > 1. - Seiichi Manyama, Aug 29 2020

A337397 Expansion of sqrt(2 / ( (1+64*x^2) * (1-8*x+sqrt(1+64*x^2)) )).

Original entry on oeis.org

1, 2, -34, -92, 1654, 4828, -88724, -268088, 4984486, 15361708, -287691196, -898052872, 16901635516, 53234639768, -1005474931816, -3187958034544, 60375963282182, 192405594166988, -3651655920615596, -11684176213422568, 222132094724096852, 713091439789994824, -13575872676384218776
Offset: 0

Views

Author

Seiichi Manyama, Aug 26 2020

Keywords

Crossrefs

Column k=4 of A337464.

Programs

  • Mathematica
    a[n_] := Sum[(-4)^(n - k) * Binomial[2*k, k] * Binomial[2*n + 1, 2*k], {k, 0, n}]; Array[a, 23, 0] (* Amiram Eldar, Aug 26 2020 *)
    CoefficientList[Series[Sqrt[2/((1+64x^2)(1-8x+Sqrt[1+64x^2]))],{x,0,30}],x] (* Harvey P. Dale, Jul 24 2021 *)
  • PARI
    N=40; x='x+O('x^N); Vec(sqrt(2/((1+64*x^2)*(1-8*x+sqrt(1+64*x^2)))))
    
  • PARI
    {a(n) = sum(k=0, n, (-4)^(n-k)*binomial(2*k, k)*binomial(2*n+1, 2*k))}

Formula

a(n) = Sum_{k=0..n} (-4)^(n-k) * binomial(2*k,k) * binomial(2*n+1,2*k).
a(0) = 1, a(1) = 2 and n * (2*n+1) * (4*n-3) * a(n) = (4*n-1) * 2 * a(n-1) - 64 * (n-1) * (2*n-1) * (4*n+1) * a(n-2) for n > 1. - Seiichi Manyama, Aug 29 2020

A337466 Expansion of sqrt(2 / ( (1-4*x+36*x^2) * (1-6*x+sqrt(1-4*x+36*x^2)) )).

Original entry on oeis.org

1, 4, -6, -120, -266, 2520, 17380, -13104, -599130, -1853544, 12391116, 108252144, 6439356, -3577917200, -14043012984, 65962248352, 730407220998, 602517029400, -22507424996420, -108316306187600, 347406564086868, 5073542740156752, 7904100039294456, -143838603813578400
Offset: 0

Views

Author

Seiichi Manyama, Aug 28 2020

Keywords

Crossrefs

Column k=2 of A337464.

Programs

  • Mathematica
    a[n_] := Sum[(-2)^(n-k) * Binomial[2*k, k] * Binomial[2*n+1, 2*k], {k, 0, n}]; Array[a, 24, 0] (* Amiram Eldar, Apr 29 2021 *)
    CoefficientList[Series[Sqrt[2/((1-4x+36x^2)(1-6x+Sqrt[1-4x+36x^2]))],{x,0,40}],x] (* Harvey P. Dale, Sep 07 2023 *)
  • PARI
    N=40; x='x+O('x^N); Vec(sqrt(2/((1-4*x+36*x^2)*(1-6*x+sqrt(1-4*x+36*x^2)))))
    
  • PARI
    {a(n) = sum(k=0, n, (-2)^(n-k)*binomial(2*k, k)*binomial(2*n+1, 2*k))}

Formula

a(n) = Sum_{k=0..n} (-2)^(n-k) * binomial(2*k,k) * binomial(2*n+1,2*k).
a(0) = 1, a(1) = 4 and n * (2*n+1) * (4*n-3) * a(n) = (4*n-1) * (8*n^2-4*n) * a(n-1) - 36 * (n-1) * (2*n-1) * (4*n+1) * a(n-2) for n > 1. - Seiichi Manyama, Aug 29 2020

A337467 Expansion of sqrt(2 / ( (1-2*x+49*x^2) * (1-7*x+sqrt(1-2*x+49*x^2)) )).

Original entry on oeis.org

1, 3, -21, -139, 531, 6489, -9723, -292293, -135117, 12514313, 29905809, -501239553, -2310673379, 18245192679, 140574917259, -562805403867, -7557237645741, 11275709877369, 371974318253601, 201852054629631, -16932135947326551, -42530838930147813, 709138646702505999
Offset: 0

Views

Author

Seiichi Manyama, Aug 28 2020

Keywords

Crossrefs

Column k=3 of A337464.

Programs

  • Mathematica
    a[n_] := Sum[(-3)^(n-k) * Binomial[2*k, k] * Binomial[2*n+1, 2*k], {k, 0, n}]; Array[a, 23, 0] (* Amiram Eldar, Apr 29 2021 *)
  • PARI
    N=40; x='x+O('x^N); Vec(sqrt(2/((1-2*x+49*x^2)*(1-7*x+sqrt(1-2*x+49*x^2)))))
    
  • PARI
    {a(n) = sum(k=0, n, (-3)^(n-k)*binomial(2*k, k)*binomial(2*n+1, 2*k))}

Formula

a(n) = Sum_{k=0..n} (-3)^(n-k) * binomial(2*k,k) * binomial(2*n+1,2*k).
a(0) = 1, a(1) = 3 and n * (2*n+1) * (4*n-3) * a(n) = (4*n-1) * (4*n^2-2*n+1) * a(n-1) - 49 * (n-1) * (2*n-1) * (4*n+1) * a(n-2) for n > 1. - Seiichi Manyama, Aug 29 2020

A337465 a(n) = Sum_{k=0..n} (-n)^(n-k) * binomial(2*k,k) * binomial(2*n+1,2*k).

Original entry on oeis.org

1, 5, -6, -139, 1654, -5853, -196860, 6258751, -112580442, 985287863, 26443436876, -1897380617625, 72596047613116, -2086036395460171, 39493340495025864, 304974352009838745, -85532651616832374010, 6040114369000387188975, -321378391411642082323524, 14224299551865677212271567
Offset: 0

Views

Author

Seiichi Manyama, Aug 28 2020

Keywords

Crossrefs

Main diagonal of A337464.

Programs

  • Mathematica
    a[n_] := Sum[If[n == n - k == 0, 1, (-n)^(n-k)] * Binomial[2*k, k] * Binomial[2*n+1, 2*k], {k, 0, n}]; Array[a, 20, 0] (* Amiram Eldar, Apr 29 2021 *)
  • PARI
    {a(n) = sum(k=0, n, (-n)^(n-k)*binomial(2*k, k)*binomial(2*n+1, 2*k))}
Showing 1-7 of 7 results.