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.

A081297 Array T(k,n), read by antidiagonals: T(k,n) = ((k+1)^(n+1)-(-k)^(n+1))/(2k+1).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 7, 5, 1, 1, 1, 13, 13, 11, 1, 1, 1, 21, 25, 55, 21, 1, 1, 1, 31, 41, 181, 133, 43, 1, 1, 1, 43, 61, 461, 481, 463, 85, 1, 1, 1, 57, 85, 991, 1281, 2653, 1261, 171, 1, 1, 1, 73, 113, 1891, 2821, 10501, 8425, 4039, 341, 1, 1, 1, 91, 145, 3305
Offset: 0

Views

Author

Paul Barry, Mar 17 2003

Keywords

Comments

Square array of solutions of a family of recurrences.
Rows of the array give solutions to the recurrences a(n)=a(n-1)+k(k-1)a(n-2), a(0)=a(1)=1.
Subarray of array in A072024. - Philippe Deléham, Nov 24 2013

Examples

			Rows begin
  1, 1,  1,  1,   1,    1, ...
  1, 1,  3,  5,  11,   21, ...
  1, 1,  7, 13,  55,  133, ...
  1, 1, 13, 25, 181,  481, ...
  1, 1, 21, 41, 461, 1281, ...
		

Crossrefs

Columns include A002061, A001844, A072025.
Diagonals include A081298, A081299, A081300, A081301, A081302.

Programs

  • Mathematica
    T[n_, k_]:=((n + 1)^(k + 1) - (-n)^(k + 1)) / (2n + 1); Flatten[Table[T[n - k, k], {n, 0, 10}, {k, 0, n}]] (* Indranil Ghosh, Mar 27 2017 *)
  • PARI
    for(k=0, 10, for(n=0, 9, print1(((k+1)^(n+1)-(-k)^(n+1))/(2*k+1), ", "); ); print(); ) \\ Andrew Howroyd, Mar 26 2017
    
  • Python
    def T(n, k): return ((n + 1)**(k + 1) - (-n)**(k + 1)) // (2*n + 1)
    for n in range(11):
        print([T(n - k, k) for k in range(n + 1)]) # Indranil Ghosh, Mar 27 2017

Formula

T(k, n) = ((k+1)^(n+1)-(-k)^(n+1))/(2k+1).
Rows of the array have g.f. 1/((1+kx)(1-(k+1)x)).

Extensions

Name clarified by Andrew Howroyd, Mar 27 2017

A081298 Main diagonal of the square array A081297.

Original entry on oeis.org

1, 1, 7, 25, 461, 2821, 84883, 734161, 30684601, 342800821, 18348174791, 251203133545, 16394732478853, 265727053328101, 20464206411678331, 383172119935376161, 34011762638354230001, 722380674949394645269
Offset: 0

Views

Author

Paul Barry, Mar 17 2003

Keywords

Crossrefs

Programs

  • Magma
    [((n+1)^(n+1)-(-n)^(n+1))/(2*n+1): n in [0..20]]; // Vincenzo Librandi, Aug 07 2013
  • Mathematica
    Table[((n + 1)^(n + 1) - (-n)^(n + 1)) / (2 n + 1),{n, 0, 20}] (* Vincenzo Librandi, Aug 07 2013 *)

Formula

a(n) = ((n+1)^(n+1)-(-n)^(n+1))/(2n+1).

A081299 Diagonal of square array A081297.

Original entry on oeis.org

1, 3, 13, 181, 1281, 32551, 314245, 11638089, 141943681, 6914792611, 101829922701, 6152865979261, 106138316846017, 7657555132292703, 151395000617362741, 12699162274678909201, 283052059672669084161
Offset: 0

Views

Author

Paul Barry, Mar 17 2003

Keywords

Crossrefs

Programs

  • Magma
    [((n+1)^(n+2)-(-n)^(n+2))/(2*n+1): n in [0..20]]; // Vincenzo Librandi, Aug 08 2013
  • Mathematica
    Table[((n + 1)^(n + 2) - (-n)^(n + 2)) / (2 n + 1), {n, 0, 20}] (* Vincenzo Librandi, Aug 08 2013 *)

Formula

a(n) = ((n+1)^(n+2)-(-n)^(n+2))/(2*n+1).

A081300 Diagonal of square array A081297.

Original entry on oeis.org

1, 5, 55, 481, 10501, 117181, 3879331, 52751105, 2351234953, 37766866501, 2120129149711, 39311679607201, 2663716583547085, 56019878838007085, 4448878347069812251, 104660471059169187841, 9534251497305019644433
Offset: 0

Views

Author

Paul Barry, Mar 17 2003

Keywords

Crossrefs

Programs

  • Magma
    [((n+1)^(n+3)-(-n)^(n+3))/(2*n+1): n in [0..20]]; // Vincenzo Librandi, Aug 07 2013
  • Mathematica
    Table[((n + 1)^(n + 3) - (-n)^(n + 3)) / (2 n + 1), {n, 0, 20}] (* Vincenzo Librandi, Aug 07 2013 *)

Formula

a(n) = ((n+1)^(n+3)-(-n)^(n+3))/(2*n+1).

A081302 Subdiagonal of square array A081297.

Original entry on oeis.org

1, 1, 21, 61, 1891, 9633, 404713, 2997541, 159902271, 1564345201, 101406750589, 1236882490845, 94479649710811, 1382731226210881, 121677107761110993, 2079381120597925237, 207197254527662127511, 4051708966720224576081
Offset: 0

Views

Author

Paul Barry, Mar 17 2003

Keywords

Crossrefs

Programs

  • Magma
    [((n+3)^(n+1)-(-(n+2))^(n+1))/(2*n+5): n in [0..20]]; // Vincenzo Librandi, Aug 08 2013
  • Mathematica
    Table[((n + 3)^(n + 1) - (-(n + 2))^(n + 1)) / (2 n + 5), {n, 0, 20}] (* Vincenzo Librandi, Aug 08 2013 *)

Formula

a(n) = ((n+3)^(n+1)-(-(n+2))^(n+1))/(2*n+5).
Showing 1-5 of 5 results.