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 1-9 of 9 results.

A131084 A129686 * A007318. Riordan triangle (1+x, x/(1-x)).

Original entry on oeis.org

1, 1, 1, 0, 2, 1, 0, 2, 3, 1, 0, 2, 5, 4, 1, 0, 2, 7, 9, 5, 1, 0, 2, 9, 16, 14, 6, 1, 0, 2, 11, 25, 30, 20, 7, 1, 0, 2, 13, 36, 55, 50, 27, 8, 1, 0, 2, 15, 49, 91, 105, 77, 35, 9, 1
Offset: 1

Views

Author

Gary W. Adamson, Jun 14 2007

Keywords

Comments

Row sums = A098011 starting (1, 2, 3, 6, 12, 24, 48, ...). A131085 = A007318 * A129686
Riordan array (1+x, x/(1-x)). - Philippe Deléham, Mar 02 2012

Examples

			The triangle T(n, k) begins:
n\k 0  1  2  3   4   5   6   7  8  9 10 ...
0:  1
1:  1  1
2:  0  2  1
3:  0  2  3  1
4:  0  2  5  4   1
5:  0  2  7  9   5   1
6:  0  2  9 16  14   6   1
7:  0  2 11 25  30  20   7   1
8:  0  2 13 36  55  50  27   8  1
9:  0  2 15 49  91 105  77  35  9  1
10: 0  2 17 64 140 196 182 112 44 10  1
... Reformatted. - _Wolfdieter Lang_, Jan 06 2015
		

Crossrefs

Formula

A129686(signed): (1,1,1,...) in the main diagonal and (-1,-1,-1, ...) in the subsubdiagonal); * A007318, Pascal's triangle; as infinite lower triangular matrices.
exp(x) * e.g.f. for row n = e.g.f. for diagonal n. For example, for n = 3 we have exp(x)*(2*x + 3*x^2/2! + x^3/3!) = 2*x + 7*x^2/2! + 16*x^3/3! + 30*x^4/4! + .... The same property holds more generally for Riordan arrays of the form ( f(x), x/(1 - x) ). - Peter Bala, Dec 22 2014
G.f. column k: (1+x)*(x/(1-x))^k, k >= 0. (Riordan property). - Wolfdieter Lang, Jan 06 2015
T(n, 0) = 1 if n=0 or n=1 else 0; T(n, k) = binomial(n-1,k-1) + binomial(n-2,k-1)*[n-1 >= k] if n >= k >= 1, where [S] = 1 if S is true, else 0, and T(n, k) = 0 if n < k. - Wolfdieter Lang, Jan 08 2015

Extensions

Edited: Added Riordan property (see Philippe Deléham comment) in name. - Wolfdieter Lang, Jan 06 2015

A129687 A129686 * A007318.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 2, 4, 3, 1, 2, 6, 7, 4, 1, 2, 8, 13, 11, 5, 1, 2, 10, 21, 24, 16, 6, 1, 2, 12, 31, 45, 40, 22, 7, 1, 2, 14, 43, 76, 85, 62, 29, 8, 1, 2, 16, 57, 119, 161, 147, 91, 37, 9, 1, 2, 18, 73, 176, 280, 308, 238, 128, 46, 10, 1, 2, 20, 91, 249, 456
Offset: 0

Views

Author

Gary W. Adamson, Apr 28 2007

Keywords

Comments

Row sums = A084215: (1, 2, 5, 10, 20, 40, 80, ...). A007318 * A129686 = A124725.
From Philippe Deléham, Feb 12 2014: (Start)
Riordan array ((1+x^2)/(1-x), x/(1-x)).
Diagonal sums are A000032(n) - 0^n (cf. A000204).
T(n,0) = A046698(n+1).
T(n+1,1) = A004277(n).
T(n+2,2) = A002061(n+1).
T(n+3,3) = A006527(n+1) = A167875(n).
T(n+4,4) = A006007(n+1).
T(n+5,5) = A081282(n+1). (End)

Examples

			First few rows of the triangle:
  1;
  1,   1;
  2,   2,   1;
  2,   4,   3,   1;
  2,   6,   7,   4,   1;
  2,   8,  13,  11,   5,   1;
  2,  10,  21,  24,  16,   6,   1;
  2,  12,  31,  45,  40,  22,   7,   1;
  2,  14,  43,  76,  85,  62,  29,   8,   1;
  2,  16,  57, 119, 161, 147,  91,  37,   9,   1;
  ...
		

Crossrefs

Formula

A129686 * A007318 (Pascal's Triangle), as infinite lower triangular matrices.
T(n,k) = T(n-1,k) + T(n-1,k-1), T(0,0) = T(1,0) = T(1,1) = T(2,2) = 1, T(2,0) = T(2,1) = 2, T(n,k) = 0 if k<0 or if k>n. - Philippe Deléham, Feb 12 2014

Extensions

More terms from Philippe Deléham, Feb 12 2014

A129688 A129686 * A128174.

Original entry on oeis.org

1, 0, 1, 2, 0, 1, 0, 2, 0, 1, 2, 0, 2, 0, 1, 0, 2, 0, 2, 0, 1, 2, 0, 2, 0, 2, 0, 1, 0, 2, 0, 2, 0, 2, 0, 1, 2, 0, 2, 0, 2, 0, 2, 0, 1, 0, 2, 0, 2, 0, 2, 0, 2, 0, 1
Offset: 1

Views

Author

Gary W. Adamson, Apr 28 2007

Keywords

Comments

Resulting triangle has (1, 0, 2, 0, 2, 0, 2, ...) in every column.
Row sums = A109613: (1, 1, 3, 3, 5, 5, ...).

Examples

			First few rows of the triangle:
  1;
  0, 1;
  2, 0, 1;
  0, 2, 0, 1;
  2, 0, 2, 0, 1;
  ...
		

Crossrefs

Programs

  • Mathematica
    T[n_, k_] := If[k == n, 1, If[EvenQ[n + k], 2, 0]];
    Table[T[n, k], {n, 1, 10}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jul 10 2019 *)

Formula

A129686 * A128174 as infinite lower triangular matrices.

A131034 A129686 * A051340.

Original entry on oeis.org

1, 2, 1, 4, 1, 1, 6, 2, 1, 1, 8, 2, 2, 1, 1, 10, 2, 2, 2, 1, 12, 2, 2, 2, 2, 1, 1, 14, 2, 2, 2, 2, 2, 1, 1, 16, 2, 2, 2, 2, 2, 2, 1, 1
Offset: 0

Views

Author

Gary W. Adamson, Jun 10 2007

Keywords

Comments

Row sums = A113127: (1, 3, 6, 10, 14, 18, 22, ...).

Examples

			First few rows of the triangle:
   1;
   2, 1;
   4, 1, 1;
   6, 2, 1, 1;
   8, 2, 2, 1, 1;
  10, 2, 2, 2, 1, 1;
  ...
		

Crossrefs

Formula

A129686 * A051340 as infinite lower triangular matrices.

A131085 Triangle T(n,k) (n>=0, 0<=k<=n-1) read by rows, A007318 * A129686.

Original entry on oeis.org

1, 1, 1, 0, 2, 1, -2, 2, 3, 1, -5, 0, 5, 4, 1, -9, -5, 5, 9, 5, 1, -14, -14, 0, 14, 14, 6, 1, -20, -28, -14, 14, 28, 20, 7, 1, -27, -48, -42, 0, 42, 48, 27, 8, 1, -35, -75, -90, -42, 42, 90, 75, 35, 9, 1, -44, -110, -165, -132, 0, 132, 165, 110, 44, 10, 1
Offset: 0

Views

Author

Gary W. Adamson, Jun 14 2007

Keywords

Comments

Row sums = n.
A131085 * A000012 = A074909 starting (1, 2, 1, 3, 3, ...) instead of (1, 1, 2, 1, 3, 3, ...).

Examples

			First few rows of the triangle are:
   1;
   1,  1;
   0,  2, 1;
  -2,  2, 3, 1;
  -5,  0, 5, 4, 1;
  -9, -5, 5, 9, 5, 1;
-14, -14, 0, 14, 14, 6, 1;
-20, -28, -14, 14, 28, 20, 7, 1;
-27, -48, -42, 0, 42, 48, 27, 8, 1;
-35, -75, -90, -42, 42, 90, 75, 35, 9, 1;
   ...
		

Crossrefs

Programs

  • PARI
    tabl(nn) = {t007318 = matrix(nn, nn, n, k, binomial(n-1, k-1)); t129686 = matrix(nn, nn, n, k, (k<=n)*((-1)^((n-k)\2)*((k==n) || (-1)*(k==(n-2))))); t131085 = t007318*t129686; for (n = 1, nn, for (k = 1, n, print1(t131085[n, k], ", ");););} \\ Michel Marcus, Feb 12 2014

Formula

Binomial transform of A129686 signed with (1, 1, 1, ...) in the main diagonal and (-1, -1, -1, ...) in the subsubdiagonal.
T(n,m) = T(n-1,m-1) + T(n-1,m). - Yuchun Ji, Dec 17 2018
T(2*k,k-1) = 0 for k > 0. - Yuchun Ji, Dec 20 2018
Comparing this triangle with the Catalan triangle A009766 one can see many similarities. For example, T(k+j,k) = A009766(k+1,j) for j < k+2. - Yuchun Ji, Dec 23 2018 [Edited by N. J. A. Sloane, Feb 11 2019]

Extensions

Missing comma corrected by Naruto Canada, Aug 26 2007
More terms from Michel Marcus, Feb 12 2014
Offset changed by N. J. A. Sloane, Feb 11 2019

A133938 A007318 * (A129686 + A133080 - I), where I is the identity matrix.

Original entry on oeis.org

1, 2, 1, 4, 2, 1, 7, 4, 4, 1, 11, 8, 11, 4, 1, 16, 15, 25, 11, 6, 1, 22, 26, 50, 26, 22, 6, 1, 29, 42, 91, 56, 63, 22, 8, 1, 37, 64, 154, 112, 154, 64, 37, 8, 1, 46, 93, 24, 210, 336, 162, 129, 37, 10, 1
Offset: 1

Views

Author

Gary W. Adamson, Sep 29 2007

Keywords

Comments

Left column = A000124: (1, 2, 4, 7, 11, ...).
Row sums = A133124: (1, 3, 7, 16, 35, 74, ...).

Examples

			First few rows of the triangle:
   1;
   2,  1;
   4,  2,  1;
   7,  4,  4,  1;
  11,  8, 11,  4,  1;
  16, 15, 25, 11,  6,  1;
  22, 26, 50, 26, 22,  6,  1;
  ...
		

Crossrefs

Formula

Binomial transform of matrix M, where M = a tridiagonal matrix with (1,1,1,...) in the main diagonal, (1,0,1,0,...) in the subdiagonal and (1,1,1,...) in the subsubdiagonal. M = (A129686 + A133080 - I), I = Identity matrix.

A130028 A129686 * A054523.

Original entry on oeis.org

1, 1, 1, 3, 0, 1, 3, 2, 0, 1, 6, 0, 1, 0, 1, 4, 3, 1, 1, 0, 1, 10, 0, 0, 0, 1, 0, 1, 6, 4, 1, 1, 0, 1, 0, 1, 12, 0, 2, 0, 0, 0, 1, 0, 1, 8, 6, 0, 1, 1, 0, 0, 1, 0, 1
Offset: 1

Views

Author

Gary W. Adamson, May 02 2007

Keywords

Comments

Row sums = A004277, 1 followed by even terms: (1, 2, 4, 6, 8, 10, ...).

Examples

			First few rows of the triangle:
   1;
   1, 1;
   3, 0, 1;
   3, 2, 0, 1;
   6, 0, 1, 0, 1;
   4, 3, 1, 1, 0, 1;
  10, 0, 0, 0, 1, 0, 1;
   6, 4, 1, 1, 0, 1, 0, 1;
  ...
		

Crossrefs

Formula

A129686 * A054523 as infinite lower triangular matrices, where A129686 = the alternate term operator.

A131035 A051340 * A129686 as infinite lower triangular matrices.

Original entry on oeis.org

1, 2, 1, 4, 1, 1, 5, 2, 1, 1, 6, 2, 2, 1, 1, 7, 2, 2, 2, 1, 1, 8, 2, 2, 2, 2, 1, 1, 9, 2, 2, 2, 2, 2, 1, 1, 10, 2, 2, 2, 2, 2, 2, 1, 1
Offset: 1

Views

Author

Gary W. Adamson, Jun 10 2007

Keywords

Comments

Row sums give A008486.

Examples

			First few rows of the triangle:
   1;
   2, 1;
   4, 1, 1;
   5, 2, 1, 1;
   6, 2, 2, 1, 1;
   7, 2, 2, 2, 1, 1;
   8, 2, 2, 2, 2, 1, 1;
   9, 2, 2, 2, 2, 2, 1, 1;
  10, 2, 2, 2, 2, 2, 2, 1, 1;
  ...
		

Crossrefs

A131258 A129686^(-1) * A052509.

Original entry on oeis.org

1, 1, 1, 0, 2, 1, 0, 2, 2, 1, 1, 2, 3, 2, 1, 1, 3, 5, 3, 2, 1, 0, 4, 8, 6, 3, 2, 1, 0, 4, 11, 12, 6, 3, 2, 1, 1, 4, 14, 20, 13, 6, 3, 2, 1, 1, 5, 18, 30, 25, 13, 6, 3, 2, 1
Offset: 0

Views

Author

Gary W. Adamson, Jun 23 2007

Keywords

Comments

Row sums = A097083: (1, 2, 3, 5, 9, 15, ...).

Examples

			First few rows of the triangle:
  1;
  1, 1;
  0, 2, 1;
  0, 2, 2, 1;
  1, 2, 3, 2, 1;
  1, 3, 5, 3, 2, 1;
  0, 4, 8, 6, 3, 2, 1;
  ...
		

Crossrefs

Formula

A129686^(-1) * A052509 as infinite lower triangular matrices, where A129686 = the alternate term operator.
Showing 1-9 of 9 results.