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 1-3 of 3 results.

A094250 Array, A(n, k) = ((n+2)^(k+1) + (k+1)*n*(n+1) - 1)/(n+1)^2, read by antidiagonals.

Original entry on oeis.org

1, 1, 3, 1, 3, 7, 1, 3, 8, 15, 1, 3, 9, 22, 31, 1, 3, 10, 31, 63, 63, 1, 3, 11, 42, 117, 185, 127, 1, 3, 12, 55, 199, 459, 550, 255, 1, 3, 13, 70, 315, 981, 1825, 1644, 511, 1, 3, 14, 87, 471, 1871, 4888, 7287, 4925, 1023, 1, 3, 15, 106, 673, 3273, 11203, 24420, 29133, 14767, 2047
Offset: 0

Views

Author

N. J. A. Sloane, Jun 02 2004

Keywords

Examples

			Array, A(n, k), begins:
  1, 3,  7, 15,  31,   63,   127,    255,     511, ... A000225;
  1, 3,  8, 22,  63,  185,   550,   1644,    4925, ... A047926;
  1, 3,  9, 31, 117,  459,  1825,   7287,   29133, ... A073724;
  1, 3, 10, 42, 199,  981,  4888,  24420,  122077, ... A094195;
  1, 3, 11, 55, 315, 1871, 11203,  67191,  403115, ... A094259;
  1, 3, 12, 70, 471, 3273, 22882, 160140, 1120941, ...
Antidiagonals, T(n, k), begins as:
  1;
  1, 3;
  1, 3,  7;
  1, 3,  8, 15;
  1, 3,  9, 22,  31;
  1, 3, 10, 31,  63,   63;
  1, 3, 11, 42, 117,  185,  127;
  1, 3, 12, 55, 199,  459,  550,  255;
  1, 3, 13, 70, 315,  981, 1825, 1644,  511;
  1, 3, 14, 87, 471, 1871, 4888, 7287, 4925, 1023;
		

Crossrefs

Programs

  • Magma
    A094250:= func< n,k | ((n-k+2)^(k+1) + (k+1)*(n-k)*(n-k+1) - 1)/(n-k+1)^2 >;
    [A094250(n,k): k in [0..n], n in [0..15]]; // G. C. Greubel, Aug 18 2023
    
  • Mathematica
    A094250[n_, k_]:= ((n-k+2)^(k+1) + (k+1)*(n-k)*(n-k+1) - 1)/(n-k+1)^2;
    Table[A094250[n, k], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Aug 18 2023 *)
  • SageMath
    def A094250(n, k): return ((n-k+2)^(k+1) + (k+1)*(n-k)*(n-k+1) - 1)/(n-k+1)^2
    flatten([[A094250(n,k) for k in range(n+1)] for n in range(16)]) # G. C. Greubel, Aug 18 2023

Formula

A(n, k) = ((n+2)^(k+1) + (k+1)*n*(n+1) - 1)/(n+1)^2 (array).
T(n, k) = ((n-k+2)^(k+1) + (k+1)*(n-k)*(n-k+1) - 1)/(n-k+1)^2 (antidiagonals).
G.f. for row n: (1-(n+1)*x)/((1-(n+2)*x)*(1-x)^2).

A094259 Expansion of g.f.: (1-5*x)/((1-6*x)*(1-x)^2).

Original entry on oeis.org

1, 3, 11, 55, 315, 1871, 11203, 67191, 403115, 2418655, 14511891, 87071303, 522427771, 3134566575, 18807399395, 112844396311, 677066377803, 4062398266751, 24374389600435, 146246337602535, 877478025615131, 5264868153690703, 31589208922144131, 189535253532864695
Offset: 0

Views

Author

N. J. A. Sloane, Jun 02 2004

Keywords

Crossrefs

Cf. A094195.
A row of A094250.

Programs

  • Magma
    [(6^(n+1) +20*n +19)/25: n in [0..40]]; // G. C. Greubel, Aug 18 2023
    
  • Mathematica
    LinearRecurrence[{8,-13,6}, {1,3,11}, 41] (* G. C. Greubel, Aug 18 2023 *)
  • SageMath
    [(6^(n+1) +20*n +19)/25 for n in range(41)] # G. C. Greubel, Aug 18 2023

Formula

a(n) = (6^(n+1) + 20*n + 19)/25.
E.g.f.: (1/25)*(6*exp(6*x) + (19 + 20*x)*exp(x)). - G. C. Greubel, Aug 18 2023

A268414 a(n) = 5*a(n-1) - 2*n for n > 0, a(0) = 1.

Original entry on oeis.org

1, 3, 11, 49, 237, 1175, 5863, 29301, 146489, 732427, 3662115, 18310553, 91552741, 457763679, 2288818367, 11444091805, 57220458993, 286102294931, 1430511474619, 7152557373057, 35762786865245, 178813934326183, 894069671630871, 4470348358154309, 22351741790771497, 111758708953857435
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 04 2016

Keywords

Comments

In general, the ordinary generating function for the recurrence relation b(n) = k*b(n - 1) - m*n, with n > 0 and b(0)=1, is (1 - (m + 2)*x + x^2)/((1 - x)^2*(1 - k*x)). This recurrence gives the closed form b(n) = ((k^2 - k*(m + 2) + 1)*k^n + m*((k - 1)*n + k))/(k - 1)^2.

Crossrefs

Programs

  • Magma
    [(4*n + 3*5^n + 5)/8: n in [0..30]]; // Vincenzo Librandi, Feb 06 2016
  • Mathematica
    Table[(4 n + 3 5^n + 5)/8, {n, 0, 23}]
    LinearRecurrence[{7, -11, 5}, {1, 3, 11}, 24]
  • PARI
    Vec((1-4*x+x^2)/((1-x)^2*(1-5*x)) + O(x^100)) \\ Altug Alkan, Feb 04 2016
    

Formula

G.f.: (1 - 4*x + x^2)/((1 - x)^2*(1 - 5*x)).
a(n) = (4*n + 3*5^n + 5)/8.
Sum_{n>=0} 1/a(n) = 1.449934283402232875...
Lim_{n -> oo} a(n + 1)/a(n) = 5.
From Elmo R. Oliveira, Sep 10 2024: (Start)
E.g.f.: exp(x)*(3*exp(4*x) + 4*x + 5)/8.
a(n) = 7*a(n-1) - 11*a(n-2) + 5*a(n-3) for n > 2. (End)

Extensions

a(24)-a(25) from Elmo R. Oliveira, Sep 10 2024
Showing 1-3 of 3 results.