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.

Previous Showing 11-13 of 13 results.

A186024 Inverse of eigentriangle of triangle A085478.

Original entry on oeis.org

1, -1, 1, -1, -1, 1, -1, -3, -1, 1, -1, -6, -5, -1, 1, -1, -10, -15, -7, -1, 1, -1, -15, -35, -28, -9, -1, 1, -1, -21, -70, -84, -45, -11, -1, 1, -1, -28, -126, -210, -165, -66, -13, -1, 1, -1, -36, -210, -462, -495, -286, -91, -15, -1, 1, -1, -45, -330, -924, -1287, -1001, -455, -120, -17, -1, 1
Offset: 0

Views

Author

Paul Barry, Feb 10 2011

Keywords

Comments

Row sums are A186025.

Examples

			Triangle begins
1,
-1, 1,
-1, -1, 1,
-1, -3, -1, 1,
-1, -6, -5, -1, 1,
-1, -10, -15, -7, -1, 1,
-1, -15, -35, -28, -9, -1, 1,
-1, -21, -70, -84, -45, -11, -1, 1,
-1, -28, -126, -210, -165, -66, -13, -1, 1,
-1, -36, -210, -462, -495, -286, -91, -15, -1, 1,
-1, -45, -330, -924, -1287, -1001, -455, -120, -17, -1, 1
		

Crossrefs

Formula

T(n,k)=if(k

A236376 Riordan array ((1-x+x^2)/(1-x)^2, x/(1-x)^2).

Original entry on oeis.org

1, 1, 1, 2, 3, 1, 3, 7, 5, 1, 4, 14, 16, 7, 1, 5, 25, 41, 29, 9, 1, 6, 41, 91, 92, 46, 11, 1, 7, 63, 182, 246, 175, 67, 13, 1, 8, 92, 336, 582, 550, 298, 92, 15, 1, 9, 129, 582, 1254, 1507, 1079, 469, 121, 17, 1, 10, 175, 957, 2508, 3718, 3367, 1925, 696, 154
Offset: 0

Author

Philippe Deléham, Jan 24 2014

Keywords

Comments

Triangle T(n,k), read by rows, given by (1, 1, -1, 1, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (1, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.
Row sums are A111282(n+1) = A025169(n-1).
Diagonal sums are A122391(n+1) = A003945(n-1).

Examples

			Triangle begins:
  1;
  1,  1;
  2,  3,   1;
  3,  7,   5,   1;
  4, 14,  16,   7,   1;
  5, 25,  41,  29,   9,  1;
  6, 41,  91,  92,  46, 11,  1;
  7, 63, 182, 246, 175, 67, 13, 1;
		

Crossrefs

Cf. Columns: A028310, A004006.
Cf. Diagonals: A000012, A005408, A130883.
Cf. Similar sequences: A078812, A085478, A111125, A128908, A165253, A207606.
Cf. A321620.

Programs

  • Maple
    # The function RiordanSquare is defined in A321620.
    RiordanSquare(1+x/(1-x)^2, 8); # Peter Luschny, Mar 06 2022
  • Mathematica
    CoefficientList[#, y] & /@
    CoefficientList[
    Series[(1 - x + x^2)/(1 - 2*x - x*y + x^2), {x, 0, 12}], x] (* Wouter Meeussen, Jan 25 2014 *)

Formula

G.f.: (1 - x + x^2)/(1 - 2*x - x*y + x^2).
T(n,k) = 2*T(n-1,k) + T(n-1,k-1) - T(n-2,k), T(0,0) = T(1,0) = T(1,1) = 1, T(2,0) = 2, T(2,1) = 3, T(2,2) = 1, T(n,k) = 0 if k < 0 or k > n.
The Riordan square (see A321620) of 1 + x/(1 - x)^2. - Peter Luschny, Mar 06 2022

A177040 Irregular triangle t(n,m) = binomial(m+1,n-m) read by rows floor((n+1)/2) <= m <= n.

Original entry on oeis.org

1, 1, 2, 1, 3, 1, 3, 4, 1, 6, 5, 1, 4, 10, 6, 1, 10, 15, 7, 1, 5, 20, 21, 8, 1, 15, 35, 28, 9, 1, 6, 35, 56, 36, 10, 1, 21, 70, 84, 45, 11, 1, 7, 56, 126, 120, 55, 12, 1, 28, 126, 210, 165, 66, 13, 1, 8, 84, 252, 330, 220, 78, 14, 1, 36, 210, 462, 495, 286, 91, 15, 1
Offset: 0

Author

Roger L. Bagula, May 01 2010

Keywords

Comments

Row sums are in A052952.
Contains the right half of each row of A030528. - R. J. Mathar, May 19 2013

Examples

			1;
1;
2, 1;
3, 1;
3, 4, 1;
6, 5, 1;
4, 10, 6, 1;
10, 15, 7, 1;
5, 20, 21, 8, 1;
15, 35, 28, 9, 1;
6, 35, 56, 36, 10, 1;
21, 70, 84, 45, 11, 1;
7, 56, 126, 120, 55, 12, 1;
28, 126, 210, 165, 66, 13, 1;
8, 84, 252, 330, 220, 78, 14, 1;
36, 210, 462, 495, 286, 91, 15, 1;
		

Crossrefs

Cf. A180987 (read diagonally downwards), A098925, A026729, A085478, A165253

Programs

  • Mathematica
    t[n_, m_] := Binomial[m + 1, n - m];
    Table[Table[t[n, m], {m, Floor[(n + 1)/2], n}], {n, 0, 15}];
    Flatten[%]
  • PARI
    T(m,n)=binomial(n+1,m-n) \\ Charles R Greathouse IV, May 19 2013
Previous Showing 11-13 of 13 results.