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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A166752 Interleave A007583 and A000012.

Original entry on oeis.org

1, 1, 3, 1, 11, 1, 43, 1, 171, 1, 683, 1, 2731, 1, 10923, 1, 43691, 1, 174763, 1, 699051, 1, 2796203, 1, 11184811, 1, 44739243, 1, 178956971, 1, 715827883, 1, 2863311531, 1, 11453246123, 1, 45812984491, 1, 183251937963, 1, 733007751851, 1
Offset: 0

Views

Author

Paul Barry, Oct 21 2009

Keywords

Comments

Partial sums are A166753.

Programs

  • Magma
    [(4*4^Floor(n/2)-1)/3 - 2*Floor(2^n/3): n in [0..25]]; // G. C. Greubel, Oct 10 2017
  • Mathematica
    LinearRecurrence[{0, 5, 0, -4}, {1, 1, 3, 1}, 100] (* G. C. Greubel, May 24 2016 *)
  • PARI
    x='x+O('x^50); Vec((1+x-2*x^2-4*x^3)/(1-5*x^2+4*x^4)) \\ G. C. Greubel, Oct 10 2017
    

Formula

G.f.: (1+x-2*x^2-4*x^3)/(1-5*x^2+4*x^4).
G.f.: (1+x)/(1-5*x^2+4*x^4) - 2*x^2*(1+2*x)/(1-5*x^2+4*x^4).
a(n) = (4*4^floor(n/2)-1)/3 - 2*floor(2^n/3).
a(n) = 4*4^floor(n/2)/3 - 2*2^n/3 - (-1)^n/3 + 2/3.
a(n) = A002450(floor(n/2)+1) - 2*A000975(n-1).

A168534 Triangle read by rows, A168532 * A000012; as infinite lower triangular matrices.

Original entry on oeis.org

1, 2, 1, 3, 1, 1, 5, 2, 1, 1, 7, 1, 1, 1, 1, 11, 4, 2, 1, 1, 1, 15, 1, 1, 1, 1, 1, 1, 22, 5, 2, 2, 1, 1, 1, 1, 30, 3, 3, 1, 1, 1, 1, 1, 1, 42, 8, 2, 2, 2, 1, 1, 1, 1, 1, 56, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 77, 14, 7, 4, 2, 2, 1, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Gary W. Adamson, Nov 28 2009

Keywords

Comments

Row sums = A078392: (1, 3, 5, 9, 11, 20, 21,...).
Triangle A168533 = A000012 * A168532
Left border = the partition numbers, A000041 starting with offset 1.

Examples

			First few rows of the triangle =
1;
2, 1;
3, 1, 1;
5, 2, 1, 1;
7, 1, 1, 1, 1;
11, 4, 2, 1, 1, 1;
15, 1, 1, 1, 1, 1, 1;
22, 5, 2, 2, 1, 1, 1, 1;
30, 3, 3, 1, 1, 1, 1, 1, 1;
42, 8, 2, 2, 2, 1, 1, 1, 1, 1;
56, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;
77, 14, 7, 4, 2, 2, 1, 1, 1, 1, 1, 1;
101, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;
135, 16, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1;
176, 9, 9, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
231, 22, 5, 5, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1;
...
		

Crossrefs

Formula

Triangle read by rows, A168532 * A000012; where A000012 = an infinite lower
triangular matrix with all 1's. The operation takes partial row sums
starting from the right of each row.

A246964 Limiting sequence of transformations when we start with the all 1's sequence a=A000012 and at step n>=0 replace a(n+a(n)) with Sum_{k=n..n+a(n)} a(k).

Original entry on oeis.org

1, 2, 1, 5, 1, 2, 1, 5, 10, 1, 2, 1, 23, 1, 2, 1, 5, 1, 39, 1, 2, 47, 50, 1, 2, 1, 5, 1, 2, 1, 5, 10, 1, 2, 1, 105, 1, 2, 1, 5, 1, 121, 1, 2, 129, 132, 1, 2, 1, 5, 1, 2, 1, 5, 10, 1, 2, 206, 432, 1, 2, 1, 5, 1, 449, 1, 2, 457, 889, 1, 2, 1, 820, 1, 2, 1, 5, 1
Offset: 0

Views

Author

Floor van Lamoen, Mar 02 2015

Keywords

Examples

			Start . . . . . . . . . . . . . . . . .       : 1,1,1,1,1,...
Step 0: a(0+a(0)) = a(1)<- a(0)+a(1) = 2      : 1,2,1,1,1,...
Step 1: a(1+a(1)) = a(3)<- a(1)+a(2)+a(3) = 4 : 1,2,1,4,1,...
Step 2: a(2+a(2)) = a(3)<- a(2)+a(3) = 5      : 1,2,1,5,1,...
		

Programs

  • Maple
    mx:= 20000:  # maximal index needed
    b:= proc() 1 end:
    a:= proc(n) option remember; global mx; local t;
          if n<0 then 0 else a(n-1); t:= b(n);
            if n+t<= mx then b(n+t):= add(b(k), k=n..n+t) fi; t
          fi
        end:
    seq(a(n), n=0..100);  # Alois P. Heinz, Mar 04 2015
  • Mathematica
    mx = 20000; (* Maximal index needed *)
    b[_] = 1;
    a[n_] := a[n] = Module[{t}, If[n<0, 0, t = b[n]; If[n+t <= mx, b[n+t] = Sum[b[k], {k, n, n+t}]]; t]];
    a /@ Range[0, 100] (* Jean-François Alcover, Nov 13 2020, after Alois P. Heinz *)

A127108 Triangle read by rows, A127099 * A000012.

Original entry on oeis.org

1, 5, 2, 7, 3, 3, 17, 10, 4, 4, 11, 5, 5, 5, 5, 35, 23, 15, 6, 6, 6, 15, 7, 7, 7, 7, 7, 7, 49, 34, 20, 20, 8, 8, 8, 8, 34, 21, 21, 9, 9, 9, 9, 9, 9, 55, 37, 25, 25, 25, 10, 10, 10, 10, 10, 23, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 119, 91, 67, 46, 30, 30, 12, 12, 12, 12, 12, 12
Offset: 0

Views

Author

Gary W. Adamson, Jan 05 2007, Jul 27 2008

Keywords

Comments

The operation A000012 * A127099 generates n-th row of the triangle by taking partial sums of n-th row of triangle A127099. Row 4 of A127099 (7, 6, 0, 4) becomes row 4 of A127108: (17, 10, 4, 4).
Row sums = A001001: (1, 7, 13, 35, 31, 91, ...).
Left column of the triangle = A060640: (1, 5, 7, 17, 11, 35, ...).

Examples

			First few rows of the triangle:
   1;
   5,  2;
   7,  3,  3;
  17, 10,  4,  4;
  11,  5,  5,  5,  5;
  35, 23, 15,  6,  6,  6;
  15,  7,  7,  7,  7,  7,  7;
  49, 34, 20, 20,  8,  8,  8,  8;
  34, 21, 21,  9,  9,  9,  9,  9,  9;
  55, 37, 25, 25, 25, 10, 10, 10, 10, 10;
  ...
		

Crossrefs

Formula

Triangle read by rows, A127099 * A000012.

Extensions

Edited by N. J. A. Sloane, Aug 13 2008 at the suggestion of R. J. Mathar

A128138 A000012 * A128132.

Original entry on oeis.org

1, 0, 2, 0, 1, 3, 0, 1, 2, 4, 0, 1, 2, 3, 5, 0, 1, 2, 3, 4, 6, 0, 1, 2, 3, 4, 5, 7, 0, 1, 2, 3, 4, 5, 6, 8, 0, 1, 2, 3, 4, 5, 6, 7, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 0, 1, 2, 3
Offset: 1

Views

Author

Gary W. Adamson, Feb 16 2007

Keywords

Examples

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

Crossrefs

Cf. A000012, A128132, A000124 (row sums).

Programs

  • Mathematica
    Table[Delete[Range[0, n], -2], {n, 14}] // Flatten (* or *)
    Table[If[k == n - 1, k + 1, k], {n, 14}, {k, 0, n - 1}] (* Michael De Vlieger, Apr 26 2016 *)

Formula

A000012 * A128132 as infinite lower triangular matrices.
T(n,n) = n.
T(n,k) = k-1, 0

A128219 A000012 * A127701. a(1) = 1, a(2) = 2, a(3) = 2; by rows, n-1 terms of 2, 3, 4, ... followed by "n".

Original entry on oeis.org

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

Author

Gary W. Adamson, Feb 19 2007

Keywords

Examples

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

Crossrefs

Cf. A000012, A127701, A034856 (row sums), A128220.

Programs

  • Mathematica
    trm[i_]:=Join[Range[2,i],{i}]; Flatten[Table[trm[n],{n,13}]] (* Harvey P. Dale, Nov 14 2012 *)

Formula

A000012 * A127701 as infinite lower triangular matrices.

A128220 Triangle, A127701 * A000012.

Original entry on oeis.org

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

Author

Gary W. Adamson, Feb 19 2007

Keywords

Comments

Row sums = A028387: (1, 5, 11, 19, 29, 41, 55, ...) A000012 * A127701 = A128219.

Examples

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

Crossrefs

Formula

A127701 * A000012 as infinite lower triangular matrices. Triangle read by rows: a(1) = 1; n-th row = (n-1) terms of (n+1) followed by "n".

A128409 Triangle read by rows: A000012 * A128408 as infinite lower triangular matrices.

Original entry on oeis.org

1, 0, -1, -1, -1, -1, -1, -1, -1, 0, -2, -1, -1, 0, -1, -1, 0, 0, 0, -1, 1, -2, 0, 0, 0, -1, 1, -1, -2, 0, 0, 0, -1, 1, -1, 0, -2, 0, 0, 0, -1, 1, -1, 0, 0, -1, 1, 0, 0, 0, 1, -1, 0, 0, 1, -2, 1, 0, 0, 0, 1, -1, 0, 0, 1, -1, -2, 1, 0, 0, 0, 1, -1, 0, 0, 1, -1, 0, -3, 1, 0, 0, 0, 1, -1, 0, 0, 1, -1, 0, -1
Offset: 1

Author

Gary W. Adamson, Mar 01 2007

Keywords

Comments

Left border = the Mertens sequence: A002321: (1, 0, -1, -1, -2, ...).
Right border = mu(n), A008683: (1, -1, -1, 0, -1, 1, -1, ...).
Row sums = A062563: (1, -1, -3, -3, -5, -1, -3, ...).

Examples

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

Crossrefs

Extensions

Previous a(51) = 0 removed and more terms from Georg Fischer, Jun 08 2023

A128521 A128174 * A054525 * A000012.

Original entry on oeis.org

1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 2, 2, 1, 1, 0, 0, 1, 2, 1, 1, 1, 3, 3, 2, 2, 1, 1, 0, 0, 1, 2, 2, 2, 1, 1, 1, 3, 3, 3, 3, 2, 2, 1, 1, 0, -1, 1, 2, 2, 3, 2, 2, 1, 1
Offset: 1

Author

Gary W. Adamson, Mar 07 2007

Keywords

Comments

Row sums = A106477: (1, 1, 3, 3, 7, 5, 13, 9, 19, 13, ...). A128522 = A054525 * A128174 * A000012.

Examples

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

Crossrefs

Formula

A128174 * A054525 * A000012 as infinite lower triangular matrices.

A128522 A054525 * A128174 * A000012.

Original entry on oeis.org

1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 3, 3, 3, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 3, 3, 3, 3, 3, 2, 2, 1, 1, 2, 2, 2, 3, 2, 3, 2, 2, 1, 1
Offset: 1

Author

Gary W. Adamson, Mar 07 2007

Keywords

Comments

Row sums = A123323: (1, 1, 3, 4, 8,7, 15, 14, ...). Left column = A083290: (1, 0, 1, 1, 2, 1, 3, 2, 3, 2, ...) A128521 = A128174 * A054525 * A000012.

Examples

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

Formula

A054525 * A128174 * A000012 as infinite lower triangular matrices.
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