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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A136579 Triangle read by rows: A128174 * A136572.

Original entry on oeis.org

1, 0, 1, 1, 0, 2, 0, 1, 0, 6, 1, 0, 2, 0, 24, 0, 1, 0, 6, 0, 120, 1, 0, 2, 0, 24, 0, 720, 0, 1, 0, 6, 0, 120, 0, 5040, 1, 0, 2, 0, 24, 0, 720, 0, 40320
Offset: 0

Views

Author

Gary W. Adamson, Jan 09 2008

Keywords

Comments

Row sums = A136580: 1, 1, 3, 7, 27, 127, ...

Examples

			First few rows of the triangle:
  1;
  0, 1;
  1, 0, 2;
  0, 1, 0, 6;
  1, 0, 2, 0, 24;
  0, 1, 0, 6,  0, 120;
  1, 0, 2, 0, 24,   0, 720;
  ...
		

Crossrefs

Formula

A128174 * A136572 Triangle, even rows = even n! interspersed with zeros. Odd n rows, = odd n! interspersed with zeros.
T(2*i,2*k) = (2*k)! = A010050(k). T(2*i+1,2*k+1) = (2*k+1)! = A009445(k). - R. J. Mathar, Jun 04 2021

A128221 A128174 * A127701.

Original entry on oeis.org

1, 1, 2, 1, 1, 3, 1, 2, 1, 4, 1, 1, 3, 1, 5, 1, 2, 1, 4, 1, 6, 1, 1, 3, 1, 5, 1, 7, 1, 2, 1, 4, 1, 6, 1, 8, 1, 1, 3, 1, 5, 1, 7, 1, 9, 1, 2, 1, 4, 1, 6, 1, 8, 1, 10, 1, 1, 3, 1, 5, 1, 7, 1, 9, 1, 11, 1, 2, 1, 4, 1, 6, 1, 8, 1, 10, 1, 12, 1, 1, 3, 1, 5, 1, 7, 1, 9, 1, 11, 1, 13
Offset: 1

Views

Author

Gary W. Adamson, Feb 19 2007

Keywords

Comments

Row sums = A024206: (1, 3, 5, 8, 11, 15, 19, ...). A128222 = A127701 * A128174.
Table T(n,k) = n, if k is odd, 1 if k is even; n, k > 0, read by antidiagonals. -Boris Putievskiy, Jan 30 2013

Examples

			From _Boris Putievskiy_, Jan 30 2013: (Start)
The start of the sequence as a table:
  1, 1, 1, 1, 1, 1, 1, ...
  2, 1, 2, 1, 2, 1, 2, ...
  3, 1, 3, 1, 3, 1, 3, ...
  4, 1, 4, 1, 4, 1, 4, ...
  5, 1, 5, 1, 5, 1, 5, ...
  6, 1, 6, 1, 6, 1, 6, ...
  7, 1, 7, 1, 7, 1, 7, ...
  ...
(End)
First few rows of the triangle are:
  1;
  1, 2;
  1, 1, 3;
  1, 2, 1, 4;
  1, 1, 3, 1, 5;
  1, 2, 1, 4, 1, 6;
  1, 1, 3, 1, 5, 1, 7;
  ...
		

Crossrefs

Programs

  • Mathematica
    a128221[n_, k_] := If[EvenQ[n-k], k, 1]/;1<=k<=n
    a128221[r_] := Table[a128221[n, k], {n, 1, r}, {k, 1, n}]
    TableForm[a128221[7]] (* triangle *)
    Flatten[a128221[10]] (* data *) (* Hartmut F. W. Hoft, Mar 08 2017 *)
    t[r_, c_] := If[ OddQ@ c, r, 1]; Table[t[k, n - k + 1], {n, 13}, {k, n}] // Flatten (* Robert G. Wilson v, Mar 09 2017 *)

Formula

A128174 * A127701 as infinite lower triangular matrices. By columns, k-th column = k, 1, k, ...; k=1,2,3,...
From Boris Putievskiy, Jan 30 2013: (Start)
As table T(n,k) = (1+(-1)^k)/2 - (-1+(-1)^k)*n/2.
As linear sequence a(n) = (1+(-1)^A004736(n))/2 - (-1+(-1)^A004736(n))*A002260(n)/2. a(n) = (1+(-1)^j)/2 - (-1+(-1)^j)*i/2,
where i = n-t*(t+1)/2, j = (t*t+3*t+4)/2-n, t=floor((-1+sqrt(8*n-7))/2). (End)

Extensions

More terms from Robert G. Wilson v, Mar 09 2017

A128618 Triangle read by rows: A128174 * A127647 as infinite lower triangular matrices.

Original entry on oeis.org

1, 0, 1, 1, 0, 2, 0, 1, 0, 3, 1, 0, 2, 0, 5, 0, 1, 0, 3, 0, 8, 1, 0, 2, 0, 5, 0, 13, 0, 1, 0, 3, 0, 8, 0, 21, 1, 0, 2, 0, 5, 0, 13, 0, 34, 0, 1, 0, 3, 0, 8, 0, 21, 0, 55, 1, 0, 2, 0, 5, 0, 13, 0, 34, 0, 89, 0, 1, 0, 3, 0, 8, 0, 21, 0, 55, 0, 144, 1, 0, 2, 0, 5, 0, 13, 0, 34, 0, 89, 0, 233
Offset: 1

Views

Author

Gary W. Adamson, Mar 14 2007

Keywords

Comments

This triangle is different from A128619, which is A128619 = A127647 * A128174.

Examples

			First few rows of the triangle are:
  1;
  0, 1;
  1, 0, 2;
  0, 1, 0, 3;
  1, 0, 2, 0, 5;
  0, 1, 0, 3, 0, 8;
  1, 0, 2, 0, 5, 0, 13;
  0, 1, 0, 3, 0, 8,  0, 21;
  1, 0, 2, 0, 5, 0, 13,  0, 34;
  0, 1, 0, 3, 0, 8,  0, 21,  0, 55;
  1, 0, 2, 0, 5, 0, 13,  0, 34,  0, 89;
  ...
		

Crossrefs

Programs

  • Magma
    [((n+k+1) mod 2)*Fibonacci(k): k in [1..n], n in [1..15]]; // G. C. Greubel, Mar 17 2024
    
  • Mathematica
    Table[Fibonacci[k]*Mod[n-k+1,2], {n,15}, {k,n}]//Flatten (* G. C. Greubel, Mar 17 2024 *)
  • SageMath
    flatten([[((n-k+1)%2)*fibonacci(k) for k in range(1,n+1)] for n in range(1,16)]) # G. C. Greubel, Mar 17 2024

Formula

By columns, Fibonacci(k) interspersed with alternate zeros in every column, k=1,2,3,...
Sum_{k=1..n} T(n, k) = A052952(n-1) (row sums).
From G. C. Greubel, Mar 17 2024: (Start)
T(n, k) = (1/2)*(1 + (-1)^(n+k))*Fibonacci(k).
T(n, n) = A000045(n).
T(2*n-1, n) = (1/2)*(1-(-1)^n)*A000045(n).
Sum_{k=1..n} (-1)^(k-1)*T(n, k) = (-1)^(n-1)*A052952(n-1).
Sum_{k=1..floor((n+1)/2)} T(n-k+1, k) = (1/2)*(1 - (-1)^n)*(Fibonacci((n+ 5)/2) - 1).
Sum_{k=1..floor((n+1)/2)} (-1)^(k-1)*T(n-k+1, k) = (1/2)*(1-(-1)^n) * A355020(floor((n-1)/2)). (End)

Extensions

a(6) corrected and more terms from Georg Fischer, May 30 2023

A128622 Triangle T(n, k) = A128064(unsigned) * A128174, read by rows.

Original entry on oeis.org

1, 1, 2, 3, 2, 3, 3, 4, 3, 4, 5, 4, 5, 4, 5, 5, 6, 5, 6, 5, 6, 7, 6, 7, 6, 7, 6, 7, 7, 8, 7, 8, 7, 8, 7, 8, 9, 8, 9, 8, 9, 8, 9, 8, 9, 9, 10, 9, 10, 9, 10, 9, 10, 9, 10, 11, 10, 11, 10, 11, 10, 11, 10, 11, 10, 11, 11, 12, 11, 12, 11, 12, 11, 12, 11, 12, 11, 12
Offset: 1

Views

Author

Gary W. Adamson, Mar 14 2007

Keywords

Examples

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

Crossrefs

Cf. A000326 (diagonal sums), A014848 (row sums), A319556 (alternating row sums).

Programs

  • Magma
    [n - ((n+k) mod 2): k in [1..n], n in [1..16]]; // G. C. Greubel, Mar 14 2024
    
  • Mathematica
    Table[n - Mod[n+k,2], {n,16}, {k,n}]//Flatten (* G. C. Greubel, Mar 14 2024 *)
  • SageMath
    flatten([[n - ((n+k)%2) for k in range(1,n+1)] for n in range(1,16)]) # G. C. Greubel, Mar 14 2024

Formula

T(n, k) = abs(A128064(n,k) * A128174(n, k), as infinite lower triangular matrices.
Sum_{k=1..n} T(n, k) = A014848(n) (row sums).
From G. C. Greubel, Mar 14 2024: (Start)
T(n, k) = n - (1 - (-1)^(n+k))/2 = n - (n+k mod 2).
T(n, 1) = A109613(n+1).
T(n, n) = A000027(n).
T(2*n-1, n) = A042963(n).
T(3*n-1, n) = A016777(n+1).
T(4*n-3, n) = A047461(n).
Sum_{k=1..n} (-1)^(k-1)*T(n, k) = A319556(n).
Sum_{k=1..floor((n+1)/2)} T(n-k+1, k) = A000326(floor((n+1)/2)).
Sum_{k=1..floor((n+1)/2)} (-1)^(k-1)*T(n-k+1, k) = A123684(floor((n+1)/2)). (End)

Extensions

More terms added by G. C. Greubel, Mar 14 2024

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.

A131228 3*A051340 - 2*A128174.

Original entry on oeis.org

1, 3, 4, 1, 3, 7, 3, 1, 3, 10, 1, 3, 1, 3, 13, 3, 1, 3, 1, 3, 16, 1, 3, 1, 3, 1, 3, 19, 3, 1, 3, 1, 3, 1, 3, 22, 1, 3, 1, 3, 1, 3, 25, 3, 1, 3, 1, 3, 1, 3, 1, 3, 28
Offset: 0

Views

Author

Gary W. Adamson, Jun 20 2007

Keywords

Comments

Row sums = A131229.

Examples

			First few rows of the triangle are:
1;
3, 4;
1, 3, 7;
3, 1, 3, 10;
1, 3, 1, 3, 13;
...
		

Crossrefs

Formula

3*A051340 - 2*A128174 as infinite lower triangular matrices.

A133728 A128174 * A127775.

Original entry on oeis.org

1, 0, 3, 1, 0, 5, 0, 3, 0, 7, 1, 0, 5, 0, 9, 0, 3, 0, 7, 0, 11, 1, 0, 5, 0, 9, 0, 13, 0, 3, 0, 7, 0, 11, 0, 15, 1, 0, 5, 0, 9, 0, 13, 0, 17, 0, 3, 0, 7, 0, 11, 0, 15, 0, 19, 1, 0, 5, 0, 9, 0, 13, 0, 17, 0, 21, 0, 3, 0, 7, 0, 11, 0, 15, 0, 19, 0, 23
Offset: 1

Views

Author

Gary W. Adamson, Sep 21 2007

Keywords

Comments

Row sums are the triangular numbers 1, 3, 6, 10, 15, 21, 28, ...; see A000217.

Examples

			From _Philippe Deléham_, Oct 28 2011: (Start)
Triangle begins:
  1;
  0,  3;
  1,  0,  5;
  0,  3,  0,  7;
  1,  0,  5,  0,  9;
  0,  3,  0,  7,  0, 11;
  1,  0,  5,  0,  9,  0, 13; ...
(End)
		

Crossrefs

Cf. A000217.

Formula

A128174 * A127775 as infinite lower triangular matrices. Triangle by columns: (2k-1, 0, 2k-1, 0, ...) in k-th column.

Extensions

Corrected and extended by Philippe Deléham, Oct 28 2011

A134317 Triangle, A128174 * A134309 as infinite lower triangular matrices.

Original entry on oeis.org

1, 0, 1, 1, 0, 2, 0, 1, 0, 4, 1, 0, 2, 0, 8, 0, 1, 0, 4, 0, 16, 1, 0, 2, 0, 8, 0, 32, 0, 1, 0, 4, 0, 16, 0, 64, 1, 0, 2, 0, 8, 0, 32, 0, 128, 0, 1, 0, 4, 0, 16, 0, 64, 0, 256
Offset: 1

Views

Author

Gary W. Adamson, Oct 19 2007

Keywords

Comments

Is this the same as A123641? - R. J. Mathar, Mar 28 2012

Examples

			First few rows of the triangle are:
1;
0, 1;
1, 0, 2;
0, 1, 0, 4;
1, 0, 2, 0, 8;
0, 1, 0, 4, 0, 16;
1, 0, 2, 0, 8, 0, 32;
0, 1, 0, 4, 0, 16, 0, 64;
...
		

Crossrefs

Cf. A128174, A134309, A001045 (row sums).

Formula

T(n,k) = 0 if n+k odd, else T(n,1) =1, T(n,k)=2^(k-2) if k>=2. - R. J. Mathar, Sep 01 2024

A134352 A130123 * A128174.

Original entry on oeis.org

1, 0, 2, 4, 0, 4, 0, 8, 0, 8, 16, 0, 16, 0, 16, 0, 32, 0, 32, 0, 32, 64, 0, 64, 0, 64, 0, 64, 0, 128, 0, 128, 0, 128, 0, 128, 256, 0, 256, 0, 256, 0, 256, 0, 256, 0, 512, 0, 512, 0, 512, 0, 512, 0, 512
Offset: 0

Views

Author

Gary W. Adamson, Oct 21 2007

Keywords

Comments

Row sums = A134353.

Examples

			First few rows of the triangle:
   1;
   0,  2;
   4,  0,  4;
   0,  8,  0,  8;
  16,  0, 16,  0, 16;
   0, 32,  0, 32,  0, 32;
  ...
		

Crossrefs

Formula

A130123 * A128174 as infinite lower triangular matrices.
Triangle read by rows: even n-th row = n+1 terms of (2^n, 0, 2^n, ...); odd n-th row = n+1 terms of (0, 2^n, 0, 2^n, ...).

A134446 A128174 * A002260.

Original entry on oeis.org

1, 1, 2, 2, 2, 3, 2, 4, 3, 4, 3, 4, 6, 4, 5, 3, 6, 6, 8, 5, 6, 4, 6, 9, 8, 10, 6, 7, 4, 8, 9, 12, 10, 12, 7, 8, 5, 8, 12, 12, 15, 12, 14, 8, 9, 5, 10, 12, 16, 15, 18, 14, 16, 9, 10
Offset: 1

Views

Author

Gary W. Adamson, Oct 25 2007

Keywords

Comments

Row sums = A002623: (1, 3, 7, 13, 22, 34, ...).

Examples

			First few rows of the triangle:
  1;
  1,  2;
  2,  2,  3;
  2,  4,  3,  4;
  3,  4,  6,  4,  5;
  3,  6,  6,  8,  5,  6;
  4,  6,  9,  8, 10,  6,  7;
  ...
		

Crossrefs

Formula

A128174 * A002260 as infinite lower triangular matrices.
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