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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A143311 Triangle read by rows, A127648 * A126988; 1<=k<=n.

Original entry on oeis.org

1, 4, 2, 9, 0, 3, 16, 8, 0, 4, 25, 0, 0, 0, 5, 36, 18, 12, 0, 0, 6, 49, 0, 0, 0, 0, 0, 7, 64, 32, 0, 16, 0, 0, 0, 8, 81, 0, 27, 0, 0, 0, 0, 0, 9, 100, 50, 0, 0, 20, 0, 0, 0, 0, 10, 121, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 144, 72, 48, 36, 0, 24, 0, 0, 0, 0, 0, 12, 169, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13
Offset: 1

Views

Author

Gary W. Adamson, Aug 06 2008

Keywords

Comments

Row sums = A064987, n*sigma(n): (1, 6, 12, 28, 30, 72, 56,...).

Examples

			First few rows of the triangle =
1;
4, 2;
9, 0, 3;
16, 8, 0, 4;
25, 0, 0, 0, 5;
36, 18, 12, 0, 0, 6;
49, 0, 0, 0, 0, 0, 7;
64, 32, 0, 16, 0, 0, 0, 8;
...
		

Crossrefs

Formula

Triangle read by rows, A127648 * A126988; 1<=k<=n

A157497 Triangle read by rows, A156348 * A127648.

Original entry on oeis.org

1, 1, 2, 1, 0, 3, 1, 4, 0, 4, 1, 0, 0, 0, 5, 1, 6, 9, 0, 0, 6, 1, 0, 0, 0, 0, 0, 7, 1, 8, 0, 16, 0, 0, 0, 8, 1, 0, 18, 0, 0, 0, 0, 0, 9, 1, 10, 0, 0, 25, 0, 0, 0, 0, 10, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 1, 12, 30, 40, 0, 36, 0, 0, 0, 0, 0, 12
Offset: 1

Views

Author

Gary W. Adamson & Mats Granvik, Mar 01 2009

Keywords

Comments

Row sums = A157020: (1, 3, 4, 9, 6, 22, 8,...)

Examples

			First few rows of the triangle =
1;
1, 2;
1, 0, 3;
1, 4, 0, 4;
1, 0, 0, 0, 5;
1, 6, 9, 0, 0, 6;
1, 0, 0, 0, 0, 0, 7;
1, 8, 0, 16, 0, 0, 0, 8;
1, 0, 18, 0, 0, 0, 0, 0, 9;
1, 10, 0, 0, 25, 0, 0, 0, 0, 10;
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11;
1, 12, 30, 40, 0, 36, 0, 0, 0, 0, 0, 12;
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13;
1, 14, 0, 0, 0, 0, 49, 0, 0, 0, 0, 0, 0, 14;
...
Row 4 = (1, 4, 0, 4) = termwise products of (1, 2, 0, 1) and (1, 2, 3, 4)
where (1, 2, 0, 1) = row 4 of triangle A156348.
		

Crossrefs

Formula

Triangle read by rows, A156348 * A127648. A127648 = an infinite lower triangular matrix with (1, 2, 3,...) as the main diagonal and the rest zeros.

A127954 Triangle, A097805 * A127648.

Original entry on oeis.org

1, 0, 2, 0, 2, 3, 0, 2, 6, 4, 0, 2, 9, 12, 5, 0, 2, 12, 24, 20, 6, 0, 2, 15, 40, 50, 30, 7, 0, 2, 18, 60, 100, 90, 42, 8, 0, 2, 21, 84, 175, 210, 147, 56, 9, 0, 2, 24, 112, 280, 420, 392, 224, 72, 10
Offset: 1

Views

Author

Gary W. Adamson, Feb 09 2007

Keywords

Comments

Row sums = A045623 starting (1, 2, 5, 12, 28, 64, ...).
Dropping the first column gives A128710. - Peter Bala, Mar 05 2013
T(n,k) is the number of ways to place n unlabeled balls into 2 boxes, make compositions of the integer number of balls in each box so that the total number of parts in both compositions is k. - Geoffrey Critzer, Sep 21 2013

Examples

			First few rows of the triangle are:
  1;
  0, 2;
  0, 2, 3;
  0, 2, 6, 4;
  0, 2, 9, 12, 5;
  0, 2, 12, 24, 20, 6;
  0, 2, 15, 40, 50, 30, 7;
  ...
T(4,3)=12. Place 4 unlabeled balls into 2 labeled boxes then make compositions of the integer number of balls in each box so that there are a total of 3 parts.
/**** 3 ways since there are 3 compositions of 4 into 3 parts.
*/***  2 ways 1;1+2  and 1;2+1
**/**  2 ways 2;1+1  and 1+1;2.
***/*  2 ways as above.
****/  3 ways as above.
3+2+2+2+3=12. - _Geoffrey Critzer_, Sep 21 2013
		

Crossrefs

Programs

  • Mathematica
    nn=10;a=x/(1-x);CoefficientList[Series[1/(1-y a)^2,{x,0,nn}],{x,y}]//Grid (* Geoffrey Critzer, Sep 21 2013 *)

Formula

A097805 * A127648 as infinite lower triangular matrices.
E.g.f.: 1/(1 - y*(x/(1-x)))^2. - Geoffrey Critzer, Sep 21 2013
O.g.f.: (1+A001263(x,y))^2, - Vladimir Kruchinin, Oct 15 2020

A143219 Triangle read by rows, A127648 * A000012 * A127773, 1 <= k <= n.

Original entry on oeis.org

1, 2, 6, 3, 9, 18, 4, 12, 24, 40, 5, 15, 30, 50, 75, 6, 18, 36, 60, 90, 126, 7, 21, 42, 70, 105, 147, 196, 8, 24, 48, 80, 120, 168, 224, 288, 9, 27, 54, 90, 135, 189, 252, 324, 405, 10, 30, 60, 100, 150, 210, 280, 360, 450, 550
Offset: 1

Views

Author

Gary W. Adamson, Jul 30 2008

Keywords

Examples

			First few rows of the triangle =
  1;
  2,  6;
  3,  9, 18;
  4, 12, 24, 40;
  5, 15, 30, 50,  75;
  6, 18, 36, 60,  90, 126;
  7, 21, 42, 70, 105, 147, 196;
  ...
		

Crossrefs

Cf. A002024, A002411 (right border), A002414, A002417 (row sums), A011379.

Programs

  • Magma
    [n*Binomial(k+1, 2): k in [1..n], n in [1..12]]; // G. C. Greubel, Jul 12 2022
    
  • Mathematica
    Table[n*Binomial[k+1, 2], {n,12}, {k,n}]//Flatten (* G. C. Greubel, Jul 12 2022 *)
  • SageMath
    flatten([[n*binomial(k+1, 2) for k in (1..n)] for n in (1..12)]) # G. C. Greubel, Jul 12 2022

Formula

Triangle read by rows, A127648 * A000012 * A127773, 1 <= k <= n.
Sum_{k=1..n} T(n, k) = A002417(n).
T(n, n) = A002411(n).
From G. C. Greubel, Jul 12 2022: (Start)
T(n, k) = A002024(n,k) * A127773(n,k).
T(n, k) = n * binomial(k+1, 2).
Sum_{k=1..floor((n+1)/2)} T(n-k+1, k) = (1/4)*(4*n - 3*floor((n+1)/2) + 3)*binomial(2 + floor((n+1)/2), 3).
T(2*n-1, n) = A002414(n), n >= 1.
T(2*n-2, n-1) = A011379(n-1), n >= 2. (End)

A143267 Triangle read by rows, A130207 * A000012 * A127648.

Original entry on oeis.org

1, 1, 2, 2, 4, 6, 2, 4, 6, 8, 4, 8, 12, 16, 20, 2, 4, 6, 8, 10, 12, 6, 12, 18, 24, 30, 36, 42, 4, 8, 12, 16, 20, 24, 28, 32, 6, 12, 18, 24, 30, 36, 42, 48, 54, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100
Offset: 1

Views

Author

Gary W. Adamson, Aug 03 2008

Keywords

Comments

Left border = phi(n), A000010.
Row sums = A143268, phi(n)*T(n): (1, 3, 12, 20, 60, 42,...)

Examples

			First few rows of the triangle =
1;
1, 2;
2, 4, 6;
2, 4, 6, 8;
4, 8, 12, 16, 20;
2, 4, 6, 8, 10, 12;
6, 12, 18, 24, 30, 36, 42;
4, 8, 12, 16, 20, 24, 28, 32;
...
Row 5 = (4, 8, 12, 16, 20) since the first terms of phi(5) = 4; so we perform (4*1, 4*2, 4*3, 4*4, 4*5).
		

Crossrefs

Formula

Triangle read by rows, A130207 * A000012 * A127648; 1<=k<=n. T(n,k) = phi(n)*k.

A143269 Triangle read by rows, A127648 * A000012 * A130207, 1<=k<=n.

Original entry on oeis.org

1, 2, 2, 3, 3, 6, 4, 4, 8, 8, 5, 5, 10, 10, 20, 6, 6, 12, 12, 24, 12, 7, 7, 14, 14, 28, 14, 42, 8, 8, 16, 16, 32, 16, 48, 32, 9, 9, 18, 18, 36, 18, 54, 36, 54, 10, 10, 20, 20, 40, 20, 60, 40, 60, 40, 11, 11, 22, 22, 44, 22, 66, 44, 66, 44, 110
Offset: 1

Views

Author

Gary W. Adamson, Aug 03 2008

Keywords

Comments

Row sums = A143270: (1, 4, 12, 24, 50, 72, 126, 176,...).

Examples

			First few rows of the triangle =
1;
2, 2;
3, 3, 6;
4, 4, 8, 8;
5, 5, 10, 10, 20;
6, 6, 12, 12, 24, 12;
7, 7, 14, 1428, 14, 42;
...
Row 5 = (5, 5, 10, 10, 20) = (5*1, 5*1, 5*2, 5*2, 5*4); where phi(k) = (1, 1, 2, 2, 4,...).
		

Crossrefs

Formula

Triangle read by rows, A127648 * A000012 * A130207. T(n,k) = n*phi(k)

A143271 Triangle read by rows: A130209 * A000012 * A127648.

Original entry on oeis.org

1, 2, 4, 2, 4, 6, 3, 6, 9, 12, 2, 4, 6, 8, 10, 4, 8, 12, 16, 20, 24, 2, 4, 6, 8, 10, 12, 14, 4, 8, 12, 16, 20, 24, 28, 32, 3, 6, 9, 12, 15, 18, 21, 24, 27, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72
Offset: 1

Views

Author

Gary W. Adamson, Aug 03 2008

Keywords

Comments

Row sums = A143272: (1, 6, 12, 30, 30, 84, 56, ...).
Left border = A000005: (1, 2, 2, 3, 2, 4, 2, 4, 3, ...).

Examples

			First few rows of the triangle =
  1;
  2, 4;
  2, 4,  6;
  3, 6,  9, 12;
  2, 4,  6,  8, 10;
  4, 8, 12, 16, 20, 24;
  2, 4,  6,  8, 10, 12, 14;
  ...
T(5,3) = 6 = 2*3 = d(5)*3.
		

Crossrefs

Programs

  • PARI
    tabl(nn) = for (n=1, nn, for (k=1, n, print1(numdiv(n)*k, ", "))); \\ Michel Marcus, Jun 05 2023

Formula

T(n,k) = d(n)*k.

Extensions

a(62) corrected by Georg Fischer, Jun 05 2023

A143273 Triangle read by rows: A127648 * A000012 * A130209.

Original entry on oeis.org

1, 2, 4, 3, 6, 6, 4, 8, 8, 12, 5, 10, 10, 15, 10, 6, 12, 12, 18, 12, 24, 7, 14, 14, 21, 14, 28, 14, 8, 16, 16, 24, 16, 32, 16, 32, 9, 18, 18, 27, 18, 36, 18, 36, 27, 10, 20, 20, 30, 20, 40, 20, 40, 30, 40, 11, 22, 22, 33, 22, 44, 22, 44, 33, 44, 22
Offset: 1

Views

Author

Gary W. Adamson, Aug 03 2008

Keywords

Comments

Row sums = A143274: (1, 6, 15, 32, 50, 84, ...).

Examples

			First few rows of the triangle =
  1;
  2,  4;
  3,  6,  6;
  4,  8,  8, 12;
  5, 10, 10, 15, 10;
  6, 12, 12, 18, 12, 24;
  7, 14, 14, 21, 14, 28, 14;
  8, 16, 16, 24, 16, 32, 16, 32;
  ...
T(6,3) = 12 = 6*d(3) = 6*2, where A000005 = d(k) = (1, 2, 3, 2, 2, 4, 2, 4, 3, ...).
		

Crossrefs

Programs

  • PARI
    tabl(nn) = for (n=1, nn, for (k=1, n, print1(n*numdiv(k), ", "))); \\ Michel Marcus, Mar 19 2016

Formula

T(n,k) = n*d(k).

Extensions

a(48) = 20 inserted by Georg Fischer, Jun 05 2023

A143442 Triangle read by rows, A127648 * A000012 * A128407, 1 <= k <= n.

Original entry on oeis.org

1, 2, -2, 3, -3, -3, 4, -4, -4, 0, 5, -5, -5, 0, -5, 6, -6, -6, 0, -6, 6, 7, -7, -7, 0, -7, 7, -7, 8, -8, -8, 0, -8, 8, -8, 0, 9, -9, -9, 0, -9, 9, -9, 0, 0, 10, -10, -10, 0, -10, 10, -10, 0, 0, 10, 11, -11, -11, 0, -11, 11, -11, 0, 0, 11, -11
Offset: 1

Views

Author

Gary W. Adamson, Aug 15 2008

Keywords

Comments

Row sums = A143443, n * (A002321, the Mertens function) = (1, 0, -3, -4, -10, -6, ...).
Right border = n*mu(n).

Examples

			First few rows of the triangle =
1;
2, -2;
3, -3, -3;
4, -4, -4, 0;
5, -5, -5, 0, -5;
6, -6, -6, 0, -6, 6;
7, -7, -7, 0, -7, 7, -7;
...
		

Crossrefs

Formula

Triangle read by rows, A127648 * A000012 * A128407, 1 <= k <= n; where A127648 = an infinite lower triangular matrix with (1, 2, 3, ...) in the main diagonal, the rest zeros. A128407 = diagonalized mu(n) matrix.

A134676 A127172 * A127648.

Original entry on oeis.org

1, 3, 2, 3, 0, 3, 6, 6, 0, 4, 3, 0, 0, 0, 5, 9, 6, 9, 0, 0, 6, 3, 0, 0, 0, 0, 0, 7, 10, 12, 0, 12, 0, 0, 0, 8, 6, 0, 9, 0, 0, 0, 0, 0, 9, 9, 6, 0, 0, 15, 0, 0, 0, 0, 10
Offset: 1

Views

Author

Gary W. Adamson, Nov 05 2007

Keywords

Comments

Left column = A007425: (1, 3, 3, 6, 3, 9, 3, 10, ...).
Row sums = A007430: (1, 5, 6, 16, 8, 30, 10, 42, ...).

Examples

			First few rows of the triangle:
  1;
  3, 2;
  3, 0, 3;
  6, 6, 0, 4;
  3, 0, 0, 0, 5;
  9, 6, 9, 0, 0, 6;
  3, 0, 0, 0, 0, 0, 7;
  ...
		

Crossrefs

Formula

A127172 * A127648 = A051731^3 * A127648 as infinite lower triangular matrices.
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