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 1-4 of 4 results.

A135852 A007318 * A103516 as a lower triangular matrix.

Original entry on oeis.org

1, 3, 2, 8, 4, 3, 20, 6, 9, 4, 48, 8, 18, 16, 5, 112, 10, 30, 40, 25, 6, 256, 12, 45, 80, 75, 36, 7, 576, 14, 63, 140, 175, 126, 49, 8, 1280, 16, 84, 224, 350, 336, 196, 64, 9, 2816, 18, 108, 336, 630, 756, 588, 288, 81, 10
Offset: 0

Views

Author

Gary W. Adamson, Dec 01 2007

Keywords

Comments

Binomial transform of triangle A103516.

Examples

			First few rows of the triangle are:
    1;
    3,  2;
    8,  4,  3;
   20,  6,  9,  4;
   48,  8, 18, 16,  5;
  112, 10, 30, 40, 25,  6;
  256, 12, 45, 80, 75, 36,  7;
  ...
		

Crossrefs

Cf. A001792 (1st column), A099035 (row sums).

Programs

  • Mathematica
    T[n_, k_]:= If[n==0, 1, If[k==0, (n+2)*2^(n-1), (k+1)*Binomial[n, k]]];
    Table[T[n, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Dec 07 2016 *)
  • Sage
    def A135852(n,k):
        if (n==0): return 1
        elif (k==0): return (n+2)*2^(n-1)
        else: return (k+1)*binomial(n, k)
    flatten([[A135852(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Feb 07 2022

Formula

T(n, k) = (A007318 * A103516)(n, k).
T(n, 0) = A001792(n).
Sum_{k=0..n} T(n, k) = A099035(n+1).
T(n, k) = (k+1)*binomial(n, k), with T(n, 0) = (n+2)*2^(n-1), T(n, n) = n+1. - G. C. Greubel, Dec 07 2016

Extensions

Offset changed to 0 by G. C. Greubel, Feb 07 2022

A135853 A103516 * A007318 as an infinite lower triangular matrix.

Original entry on oeis.org

1, 4, 2, 6, 6, 3, 8, 12, 12, 4, 10, 20, 30, 20, 5, 12, 30, 60, 60, 30, 6, 14, 42, 105, 140, 105, 42, 7, 16, 56, 168, 280, 280, 168, 56, 8, 18, 72, 252, 504, 630, 504, 252, 72, 9, 20, 90, 360, 840, 1260, 1260, 840, 360, 90, 10
Offset: 0

Views

Author

Gary W. Adamson, Dec 01 2007

Keywords

Examples

			First few rows of the triangle are:
   1;
   4,   2;
   6,   6,  3;
   8,  12,  12,   4;
  10,  20,  30,  20,   5;
  12,  30,  60,  60,  30,   6;
  14,  42, 105, 140, 105,  42,   7;
  ...
		

Crossrefs

Cf. A103517 (1st column), A135854 (row sums).

Programs

  • Mathematica
    T[n_, k_]:= If[k==n, n+1, If[k==0, 2*(n+1), (k+1)*Binomial[n+1, k+1]]];
    Table[T[n, k], {n,0,12}, {k,0,n}]//flatten (* G. C. Greubel, Dec 07 2016 *)
  • Sage
    def A135853(n,k):
        if (n==0): return 1
        elif (k==0): return 2*(n+1)
        else: return (k+1)*binomial(n+1, k+1)
    flatten([[A135853(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Feb 06 2022

Formula

T(n, k) = (A103516 * A007318)(n, k).
Sum_{k=0..n} T(n, k) = A135854(n).
T(n, k) = (k+1)*binomial(n+1, k+1), with T(n, n) = n+1, T(n, 0) = 2*(n+1). - G. C. Greubel, Dec 07 2016
T(n, 0) = A103517(n). - G. C. Greubel, Feb 06 2022

A187012 Antidiagonal sums of A103516.

Original entry on oeis.org

1, 2, 5, 4, 8, 6, 11, 8, 14, 10, 17, 12, 20, 14, 23, 16, 26, 18, 29, 20, 32, 22, 35, 24, 38, 26, 41, 28, 44, 30, 47, 32, 50, 34, 53, 36, 56, 38, 59, 40, 62, 42, 65, 44, 68, 46, 71, 48, 74, 50, 77, 52, 80, 54, 83, 56, 86, 58, 89, 60, 92, 62, 95, 64
Offset: 2

Views

Author

Michel Marcus, Aug 30 2013

Keywords

Comments

This sequence differs from A081556 at least for n=24 (see comment about n=24 in A081556).

Programs

  • Mathematica
    CoefficientList[Series[(1 + 2 x + 3 x^2 - x^4)/((1 - x)^2 (1 + x)^2), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 24 2014 *)
  • PARI
    a(n) = sum(k=0, n\2, 0^(k*(n-2*k))*(n-k+1)); \\ Michel Marcus, Aug 30 2013

Formula

a(n) = sum{k=0..floor(n/2), 0^(k(n-2k))*(n-k+1)}. - Paul Barry, Aug 30 2013
G.f. : x^2*(1+2*x+3*x^2-x^4)/((1-x)^2*(1+x)^2).
a(n) = A080512(n) - 1 for n>2.

A103517 Expansion of (1+2*x-x^2)/(1-x)^2.

Original entry on oeis.org

1, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126
Offset: 0

Views

Author

Paul Barry, Feb 09 2005

Keywords

Comments

Row sums of A103516.
Also the number of maximal and maximum cliques in the (n+1) X (n+1) rook graph. - Eric W. Weisstein, Sep 14 2017
Also the number of maximal and maximum independent vertex sets in the (n+1) X (n+1) rook complement graph. - Eric W. Weisstein, Sep 14 2017

Crossrefs

Cf. A103516.
Essentially the same as A004277, A005843, A051755, and A076032. - R. J. Mathar, Jul 31 2010
Cf. A272651 (for which this sequence is a conjectured continuation for large n).

Programs

Formula

a(n) = 2*n + 2 - 0^n.
a(n) = Sum_{k=0..n} 0^(k(n-k))*(n+1).
Equals binomial transform of [1, 3, -1, 1, -1, 1, ...]. - Gary W. Adamson, Apr 23 2008
a(n) = 2*a(n-1) - a(n-2) for n > 2. - Eric W. Weisstein, Sep 14 2017
G.f.: (1 + 2*x - x^2)/(-1 + x)^2. - Eric W. Weisstein, Sep 14 2017
Showing 1-4 of 4 results.