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.

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A133821 Triangle whose rows are sequences of increasing fourth powers: 1; 1,16; 1,16,81; ... .

Original entry on oeis.org

1, 1, 16, 1, 16, 81, 1, 16, 81, 256, 1, 16, 81, 256, 625, 1, 16, 81, 256, 625, 1296, 1, 16, 81, 256, 625, 1296, 2401, 1, 16, 81, 256, 625, 1296, 2401, 4096, 1, 16, 81, 256, 625, 1296, 2401, 4096, 6561, 1, 16, 81, 256, 625, 1296, 2401, 4096, 6561, 10000
Offset: 1

Views

Author

Peter Bala, Sep 25 2007

Keywords

Comments

Reading the triangle by rows produces the sequence 1,1,16,1,16,81,1,16,81,256,..., analogous to A002260.

Examples

			Triangle starts
1;
1, 16;
1, 16; 81;
1, 16, 81, 256;
1, 16, 81, 256, 625;
		

Crossrefs

Cf. A000538 (row sums), A002260, A133819, A133820, A133824.

Programs

  • Haskell
    a133821 n k = a133821_tabl !! (n-1) !! (k-1)
    a133821_row n = a133821_tabl !! (n-1)
    a133821_tabl = map (`take` (tail a000583_list)) [1..]
    -- Reinhard Zumkeller, Nov 11 2012
  • Mathematica
    Module[{nn=10,fp},fp=Range[(nn(nn+1))/2]^4;Table[TakeList[fp,{n}],{n,nn}]]//Flatten (* Requires Mathematica version 11 or later *) (* Harvey P. Dale, Mar 29 2020 *)

Formula

O.g.f.: (1+11qx+11q^2x^2+q^3x^3)/((1-x)(1-qx)^5) = 1 + x(1 + 16q) + x^2(1 + 16q + 81q^2) + ... . Cf. 4th row of A008292.

Extensions

Offset changed by Reinhard Zumkeller, Nov 11 2012

A143814 Triangle T(n,m) read along rows: T(n,m) = n^2 - (m+1)^2 for 1<=m

Original entry on oeis.org

3, 5, 8, 12, 7, 15, 21, 16, 9, 24, 32, 27, 20, 11, 35, 45, 40, 33, 24, 13, 48, 60, 55, 48, 39, 28, 15, 63, 77, 72, 65, 56, 45, 32, 17, 80, 96, 91, 84, 75, 64, 51, 36, 19, 99, 117, 112, 105, 96, 85, 72, 57, 40, 21, 120, 140, 135, 128, 119, 108, 95, 80, 63, 44, 23, 143
Offset: 2

Views

Author

Paul Curtz, Sep 02 2008

Keywords

Comments

The triangle appears taking the entries of A140978,
4;
9,9;
16,16,16;
25,25,25,25;
..
minus the entries of A133819 with the 1's moved to the end of the rows,
1;
4,1;
4,9,1;
4,9,16,1;
4,9,16,25,1;
The result T(n,m) is a variant of A120070, the first term in each row of A120070 transferred to the end of the row.

Examples

			3;
5,8;
12,7,15;
21,16,9,24;
32,27,20,11,35;
		

Crossrefs

Cf. A016061 (row sums).

Programs

A143844 Triangle T(n,k) = k^2 read by rows.

Original entry on oeis.org

0, 0, 1, 0, 1, 4, 0, 1, 4, 9, 0, 1, 4, 9, 16, 0, 1, 4, 9, 16, 25, 0, 1, 4, 9, 16, 25, 36, 0, 1, 4, 9, 16, 25, 36, 49, 0, 1, 4, 9, 16, 25, 36, 49, 64, 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121
Offset: 0

Views

Author

Paul Curtz, Sep 03 2008

Keywords

Comments

This is triangle A133819 with an additional leading column of zeros.
There is a family of even integer-valued polynomials p_n(x) = product_{k=0..n} (x^2 - T(n,k))/ A002674(n+1). We find p_0(x) in A000290, p_1(x) in A002415, p_2(x) essentially in A040977, p_3(x) in A053347 and p_4(x) in A054334. - Paul Curtz, Jun 10 2011

Crossrefs

Programs

Formula

T(n,k) = (A002262(n,k))^2.
G.f.: x*y*(1 + x*y)/((1 - x)*(1 - x*y)^3). - Stefano Spezia, Feb 21 2024

Extensions

Definition simplified by R. J. Mathar, Sep 07 2009
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