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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A357186 Take the k-th composition in standard order for each part k of the n-th composition in standard order, then add up everything.

Original entry on oeis.org

0, 1, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 4, 5, 5, 5, 4, 4, 5, 5, 4, 5, 5, 5, 3, 4, 5, 5, 4, 5, 5, 5, 5, 5, 6, 6, 5, 6, 6, 6, 4, 5, 5, 5, 5, 6, 6, 6, 5, 5, 6, 6, 5, 6, 6, 6, 3, 4, 5, 5, 5, 6, 6, 6, 5, 5, 6, 6, 5, 6, 6, 6, 5, 6, 6, 6, 6, 7, 7
Offset: 0

Views

Author

Gus Wiseman, Sep 28 2022

Keywords

Comments

The k-th composition in standard order (graded reverse-lexicographic, A066099) is obtained by taking the set of positions of 1's in the reversed binary expansion of k, prepending 0, taking first differences, and reversing again. This gives a bijective correspondence between nonnegative integers and integer compositions.

Examples

			Composition 92 in standard order is (2,1,1,3), with compositions ((2),(1),(1),(1,1)) so a(92) = 2 + 1 + 1 + 1 + 1 = 6.
		

Crossrefs

See link for sequences related to standard compositions.
This is the sum of A029837 over the n-th composition in standard order.
Vertex degrees are A133494.
The version for Heinz numbers of partitions is A325033.
Row sums of A357135.
First differences are A357187.

Programs

  • Mathematica
    stc[n_]:=Differences[Prepend[Join @@ Position[Reverse[IntegerDigits[n,2]],1],0]]//Reverse;
    Table[stc/@stc[n]/.List->Plus,{n,0,100}]

Formula

a(n) = A029837(A357134(n)).

A101692 A modular binomial sum transform of 2^n.

Original entry on oeis.org

1, 1, 5, 1, 5, 17, 85, 1, 5, 17, 85, 257, 1285, 4369, 21845, 1, 5, 17, 85, 257, 1285, 4369, 21845, 65537, 327685, 1114129, 5570645, 16843009, 84215045, 286331153, 1431655765, 1, 5, 17, 85, 257, 1285, 4369, 21845, 65537, 327685, 1114129, 5570645, 16843009, 84215045
Offset: 0

Views

Author

Paul Barry, Dec 11 2004

Keywords

Comments

a(2^n) is 1, 5, 5, 5, 5, ...
a(2^n+1) is 5, 1, 17, 17, 17, ...
a(2*(2^n+1)) is 5, 85, 85, 85, ...
a(2^n)*a(2^n+1) is 5, 5, 85, 85, 85, ...
Also, decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 4", based on the 5-celled von Neumann neighborhood. Initialized with a single black (ON) cell at stage zero. - Robert Price, Nov 03 2016

References

  • S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 170.

Crossrefs

Programs

  • Mathematica
    a[n_]:= Sum[Mod[Binomial[2*n+2, k],2]*2^k,{k,0,n}]; Array[a,43,0] (* Stefano Spezia, Aug 04 2025 *)

Formula

a(n) = Sum_{k=0..n} (binomial(2*n+2, k) mod 2)*2^k.
a(n) = Sum_{k=0..n} A128937(n, k)*2^(n-k). - Philippe Deléham, Oct 09 2007

A128937 Triangle formed by reading A039598 mod 2.

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1
Offset: 0

Views

Author

Philippe Deléham, Apr 27 2007, May 02 2007

Keywords

Comments

Also triangle formed by reading triangles A052179, A053121, A124575, A126075, A126093.
Also triangle formed by reading A065600 mod 2. - Philippe Deléham, Oct 15 2007

Examples

			Triangle begins:
  1;
  0, 1;
  1, 0, 1;
  0, 0, 0, 1;
  0, 0, 1, 0, 1;
  0, 1, 0, 0, 0, 1;
  1, 0, 1, 0, 1, 0, 1;
  0, 0, 0, 0, 0, 0, 0, 1;
  0, 0, 0, 0, 0, 0, 1, 0, 1;
  0, 0, 0, 0, 0, 1, 0, 0, 0, 1;
  0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1;
  0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1;
  0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1;
  0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1;
  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1;
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1; ...
		

Crossrefs

Cf. A048896 (row sums).

Programs

Formula

Sum_{k=0..n} T(n,k) = A048896(n).
Sum_{k=0..n} T(n,k)*2^(n-k) = A101692(n). - Philippe Deléham, Oct 09 2007
Sum_{k=0..n} T(n,k)*2^k = A062878(n+1)/3. - Philippe Deléham, Aug 31 2009

A133179 A modular binomial sum transform of 2^n .

Original entry on oeis.org

1, 1, 1, 3, 1, 3, 5, 15, 1, 3, 5, 15, 17, 51, 85, 255, 1, 3, 5, 15, 17, 51, 85, 255, 257, 771, 1285, 3855, 4369, 13107, 21845, 65535, 1, 3, 5, 15, 17, 51, 85, 255, 257, 771, 1285, 3855, 4369, 13107, 21845, 65535
Offset: 0

Views

Author

Philippe Deléham, Oct 10 2007

Keywords

Examples

			A034868 is:
1;
1;
1, 2;
1, 3;
1, 4, 6;
1, 5, 10 ;...
A034868 modulo 2:
1;
1;
1, 0;
1, 1;
1, 0, 0;
1, 1, 0 ;...
a(0)=1*2^0 = 1;
a(1)=1*2^0 = 1;
a(2)=1*2^0+0*2^1 = 1;
a(3)=1*2^0+1*2^1 = 3;
a(4)=1*2^0+0*2^1+0*2^2 = 1
a(5)=1*2^0+1*2^1+0*2^2 = 3
		

Crossrefs

Programs

  • Mathematica
    A133179[n_] := Sum[2^k*Mod[Binomial[n, k], 2], {k, 0, Floor[n/2]}]; Table[A133179[n], {n,0,50}] (* G. C. Greubel, Aug 11 2017 *)

Formula

a(n) = Sum_{k=0..floor(n/2)} mod(binomial(n,k),2) * 2^k.

A347928 Triangle read by rows, T(n, k) are the coefficients of the scaled Mandelbrot-Larsen polynomials P(n, x) = 2^(2*n-1)*M(n, x), where M(n, x) are the Mandelbrot-Larsen polynomials; for 0 <= k <= n.

Original entry on oeis.org

0, 0, 1, 0, 2, 1, 0, 0, 4, 2, 0, 16, 12, 12, 5, 0, 0, 32, 40, 40, 14, 0, 0, 192, 208, 168, 140, 42, 0, 0, 0, 640, 800, 720, 504, 132, 0, 2048, 1792, 2688, 3920, 3584, 3080, 1848, 429, 0, 0, 4096, 4608, 11520, 17760, 16512, 13104, 6864, 1430
Offset: 0

Views

Author

Peter Luschny, Oct 27 2021

Keywords

Comments

To avoid confusion: the polynomials which are called 'Mandelbrot polynomials' by some authors are listed in A137560. The name 'Mandelbrot-Larsen' polynomials was introduced in Calkin, Chan, & Corless to distinguish them from the Mandelbrot polynomials.

Examples

			Triangle starts:
[0]  0;
[1]  0,    1;
[2]  0,    2,    1;
[3]  0,    0,    4,    2;
[4]  0,   16,   12,   12,     5;
[5]  0,    0,   32,   40,    40,    14;
[6]  0,    0,  192,  208,   168,   140,    42;
[7]  0,    0,    0,  640,   800,   720,   504,   132;
[8]  0, 2048, 1792, 2688,  3920,  3584,  3080,  1848,  429;
[9]  0,    0, 4096, 4608, 11520, 17760, 16512, 13104, 6864, 1430.
		

Crossrefs

Programs

  • Maple
    M := proc(n, x) local k; option remember;
    if n = 0 then 0 elif n = 1 then x else add(M(k, x)*M(n-k, x), k = 1..n-1) +
    ifelse(n::even, M(n/2, x), 0) fi; expand(%/2) end:
    P := n -> 2^(2*n - 1)*M(n, x):
    row := n -> seq(coeff(P(n), x, k), k = 0..n): seq(row(n), n = 0..9);
  • Mathematica
    M[n_, x_] := M[n, x] = Module[{k, w}, w = Which[n == 0, 0, n == 1, x, True, Sum[M[k, x]*M[n-k, x], {k, 1, n-1}] + If[EvenQ[n], M[n/2, x], 0]]; Expand[w/2]];
    P[n_] := 2^(2*n - 1)*M[n, x];
    row [n_] := If[n == 0, {0}, CoefficientList[P[n], x]];
    Table[row[n], {n, 0, 9}] // Flatten (* Jean-François Alcover, Jul 07 2022, after Maple code *)

Formula

The Mandelbrot-Larsen polynomials are defined: M(0, x) = 0; M(1, x) = x/2;
M(n, x) = (1/2)*(even(n)*M(n/2, x) + Sum_{k=1..n-1} M(k, x)*M(n-k, x)) for n > 1. Here even(n) = 1 if n is even, otherwise 0.
P(n, x) = 2^(2*n-1)*M(n, x) (scaled Mandelbrot-Larsen polynomials).
T(n, k) = [x^k] P(n, x).
[x^k] M(n,k) = A348679(n, k) / A348678(n, k).
M(n, 2*k) = P(n, 2*k) / 2^(2*n-1) = A319539(n, k).
P(n, k) = A348686(n, k).
T(n, n) = A000108(n-1) for n >= 1, Catalan numbers.
T(n+2, n+1) / 2 = A000984(n) for n >= 0, central binomials.
P(n, 1) = A088674(n-1) for n >= 1, also row sums.
M(n, 2) = A001190(n) for n >= 0.
M(n, 4) = A083563(n) for n >= 0.
M(n,-4) = -A107087(n) for n >= 1.
M(n, 6) = A220816(n) for n >= 1.
M(n, 8) = A220817(n) for n >= 1.
Conjecture (Calkin, Chan, & Corless): content(P(n)) = gcd(row(n)) = A048896(n-1) for n >= 1.

A130047 Left half of Pascal's triangle (A034868) modulo 2.

Original entry on oeis.org

1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Philippe Deléham, Oct 10 2007

Keywords

Comments

Row sums yield: 1, 1, 1, 2, 1, 2, 2, 4, 1, 2, 2, 4, 2, 4, 4, 8, 1, 2, 2, 4, 2, 4, 4, 8, ...(see A048896).

Examples

			Triangle begins:
1,
1,
1, 0,
1, 1,
1, 0, 0,
1, 1, 0,
1, 0, 1, 0,
1, 1, 1, 1,
1, 0, 0, 0, 0,
1, 1, 0, 0, 0,
1, 0, 1, 0, 0, 0,
1, 1, 1, 1, 0, 0,
1, 0, 0, 0, 1, 0, 0,
1, 1, 0, 0, 1, 1, 0,
1, 0, 1, 0, 1, 0, 1, 0,
1, 1, 1, 1, 1, 1, 1, 1,
1, 0, 0, 0, 0, 0, 0, 0, 0,
...
Triangle (right aligned) begins:
                                  1,
                                1,
                              1,  0,
                            1,  1,
                          1,  0,  0,
                        1,  1,  0,
                      1,  0,  1,  0,
                    1,  1,  1,  1,
                  1,  0,  0,  0,  0,
                1,  1,  0,  0,  0,
              1,  0,  1,  0,  0,  0,
            1,  1,  1,  1,  0,  0,
          1,  0,  0,  0,  1,  0,  0,
        1,  1,  0,  0,  1,  1,  0,
      1,  0,  1,  0,  1,  0,  1,  0,
    1,  1,  1,  1,  1,  1,  1,  1,
  1,  0,  0,  0,  0,  0,  0,  0,  0,
1,  1,  0,  0,  0,  0,  0,  0,  0,
...
		

Crossrefs

Programs

  • Maple
    # From N. J. A. Sloane, Mar 22 2015:
    for n from 0 to 20 do
    lprint(seq(binomial(n,k) mod 2, k=0..floor(n/2))); od:
    # For row sums:
    f:=n->add(binomial(n,k) mod 2, k=0..floor(n/2));
    [seq(f(n),n=0..60)];
  • Mathematica
    Table[Mod[Binomial[n, k], 2], {n, 0, 10}, {k, 0, Floor[n/2]}] (* G. C. Greubel, Aug 12 2017 *)

Formula

T(n,k) = mod(binomial(n, k), 2), 0 <= k <= floor(n/2). - G. C. Greubel, Aug 12 2017

Extensions

Corrected by N. J. A. Sloane, Mar 22 2015 at the suggestion of Kevin Ryde

A151784 a(n) = 6^(wt(n) - 1) where wt(n) = A000120(n).

Original entry on oeis.org

1, 1, 6, 1, 6, 6, 36, 1, 6, 6, 36, 6, 36, 36, 216, 1, 6, 6, 36, 6, 36, 36, 216, 6, 36, 36, 216, 36, 216, 216, 1296, 1, 6, 6, 36, 6, 36, 36, 216, 6, 36, 36, 216, 36, 216, 216, 1296, 6, 36, 36, 216, 36, 216, 216, 1296, 36, 216, 216, 1296, 216, 1296, 1296, 7776, 1, 6, 6, 36, 6, 36, 36
Offset: 1

Views

Author

N. J. A. Sloane, Jun 25 2009

Keywords

Examples

			From _Omar E. Pol_, Jul 21 2009: (Start)
If written as a triangle:
  1;
  1,6;
  1,6,6,36;
  1,6,6,36,6,36,36,216;
  1,6,6,36,6,36,36,216,6,36,36,216,36,216,216,1296;
  1,6,6,36,6,36,36,216,6,36,36,216,36,216,216,1296,6,36,36,216,36,216,216,...
(End)
		

Crossrefs

Programs

  • PARI
    a(n) = 6^(hammingweight(n)-1); \\ Michel Marcus, Nov 15 2022

A167364 Triangle read by rows, A047999 * A010060 (diagonalized); as infinite lower triangular matrices.

Original entry on oeis.org

1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0
Offset: 1

Views

Author

Gary W. Adamson & Mats Granvik, Nov 01 2009

Keywords

Comments

Row sums = A048896: (1, 1, 2, 1, 2, 2, 4, 1, 2, 2, 4,...). Right border = Thue-Morse sequence A010060, starting with offset 1.

Examples

			First few rows of the triangle =
1;
0, 1;
1, 1, 0;
0, 0, 0, 1;
1, 0, 0, 1, 0;
0, 1, 0, 1, 0, 0;
1, 1, 0, 1, 0, 0, 1;
0, 0, 0, 0, 0, 0, 0, 1;
1, 0, 0, 0, 0, 0, 0, 1, 0;
0, 1, 0, 0, 0, 0, 0, 1, 0, 0;
1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1;
0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0
1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1;
0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1;
1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0;
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0;
0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0;
1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1;
...
		

Crossrefs

Formula

Let S = Sierpinski's gasket, A047999. Let Q = a diagonalized version of the Thue-Morse sequence, A010060: [0; 0,1; 0,0,1; 0,0,0,0; 0,0,0,0,1;...], (i.e. A010060 as the rightmost diagonal and the rest zeros). A167364 = S * Q, as infinite lower triangular matrices. Delete leftmost column of zeros.

A243036 Number of entries of length n in A240602.

Original entry on oeis.org

2, 1, 2, 1, 2, 2, 4, 1, 2, 2, 4, 2, 4, 4, 8, 1, 2, 2, 4, 2, 4, 4, 8, 2, 4, 4, 8, 4, 8, 8, 16, 1, 2, 2, 4, 2, 4, 4, 8, 2, 4, 4, 8, 4, 8, 8, 16, 2, 4, 4, 8, 4, 8, 8, 16, 4, 8, 8, 16, 8, 16, 16, 32, 1, 2, 2, 4, 2, 4, 4, 8, 2, 4, 4, 8, 4, 8, 8, 16, 2, 4, 4, 8, 4
Offset: 1

Views

Author

Lior Manor, May 29 2014

Keywords

Comments

For n>0, a(2^n) = 1.
For any base b, a(1) = b, a(2) = b-1, a(3) = b*(b-1), for m>1, a(2m) = a(m), a(2m+1) = b*a(m).
For any base b, a(n) = (b-1)*b^(A000120(n)-1).
Essentially the same as A048896. - R. J. Mathar, Jun 27 2014

Crossrefs

Formula

a(1) = 2, a(2) = 1, a(3) = 2, For m>1, a(2m) = a(m), a(2m+1) = 2*a(m).
a(n) = 2^(A000120(n)-1).

A256257 6 times numbers of Gould's sequence A001316.

Original entry on oeis.org

6, 12, 12, 24, 12, 24, 24, 48, 12, 24, 24, 48, 24, 48, 48, 96, 12, 24, 24, 48, 24, 48, 48, 96, 24, 48, 48, 96, 48, 96, 96, 192, 12, 24, 24, 48, 24, 48, 48, 96, 24, 48, 48, 96, 48, 96, 96, 192, 24, 48, 48, 96, 48, 96, 96, 192, 48, 96, 96, 192, 96, 192, 192, 384, 12, 24, 24, 48, 24, 48, 48, 96, 24, 48, 48, 96, 48, 96, 96, 192
Offset: 0

Views

Author

Omar E. Pol, Mar 20 2015

Keywords

Comments

Also, number of triangular cells turned ON at (n+1)-st stage in the structure of A256256.
First differences of A256256.

Examples

			Written as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins:
6;
12;
12, 24;
12, 24, 24, 48;
12, 24, 24, 48, 24, 48, 48, 96;
12, 24, 24, 48, 24, 48, 48, 96, 24, 48, 48, 96, 48, 96, 96, 192;
...
		

Crossrefs

Formula

a(n) = 6*A001316(n) = 3*A117973(n) = 2*A160713(n).
a(n) = 12*A048896(n-1), n >= 1.
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