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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A256258 Triangle read by rows in which the row lengths are the terms of A011782 and row n lists the terms of A016969 except for the right border which gives the positive terms of A000225.

Original entry on oeis.org

1, 3, 5, 7, 5, 11, 17, 15, 5, 11, 17, 23, 29, 35, 41, 31, 5, 11, 17, 23, 29, 35, 41, 47, 53, 59, 65, 71, 77, 83, 89, 63, 5, 11, 17, 23, 29, 35, 41, 47, 53, 59, 65, 71, 77, 83, 89, 95, 101, 107, 113, 119, 125, 131, 137, 143, 149, 155, 161, 167, 173, 179, 185, 127, 5, 11, 17, 23, 29, 35, 41, 47, 53, 59, 65, 71, 77, 83, 89, 95, 101, 107, 113, 119, 125, 131, 137
Offset: 1

Views

Author

Omar E. Pol, Apr 04 2015

Keywords

Comments

Row sums give A002001.
The sum of all terms of first n rows gives A000302(n-1).
The rows of triangle A256263 converge to this sequence.
Rows converge to A016969.
First 11 terms agree with A151548.

Examples

			Written as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins:
1;
3;
5,7;
5,11,17,15;
5,11,17,23,29,35,41,31;
5,11,17,23,29,35,41,47,53,59,65,71,77,83,89,63;
5,11,17,23,29,35,41,47,53,59,65,71,77,83,89,95,101,107,113,119,125,131,137,143,149,155,161,167,173,179,185,127;
...
Illustration of initial terms in the fourth quadrant of the square grid:
------------------------------------------------------------------------
n   a(n)             Compact diagram
------------------------------------------------------------------------
.            _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
1    1      |_| | | |_ _  | |_ _ _ _ _ _  | |
2    3      |_ _| | |_  | | |_ _ _ _ _  | | |
3    5      |_ _ _| | | | | |_ _ _ _  | | | |
4    7      |_ _ _ _| | | | |_ _ _  | | | | |
5    5      | | |_ _ _| | | |_ _  | | | | | |
6   11      | |_ _ _ _ _| | |_  | | | | | | |
7   17      |_ _ _ _ _ _ _| | | | | | | | | |
8   15      |_ _ _ _ _ _ _ _| | | | | | | | |
9    5      | | | | | | |_ _ _| | | | | | | |
10  11      | | | | | |_ _ _ _ _| | | | | | |
11  17      | | | | |_ _ _ _ _ _ _| | | | | |
12  23      | | | |_ _ _ _ _ _ _ _ _| | | | |
13  29      | | |_ _ _ _ _ _ _ _ _ _ _| | | |
14  35      | |_ _ _ _ _ _ _ _ _ _ _ _ _| | |
15  41      |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _| |
16  31      |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|
.
a(n) is also the number of cells in the n-th region of the diagram.
It appears that A241717 can be represented by a similar diagram.
		

Crossrefs

Programs

  • Mathematica
    Nest[Join[#, Range[Length[#] - 1]*6 - 1, {2 #[[-1]] + 1}] &, {1}, 7] (* Ivan Neretin, Feb 14 2017 *)

A162958 Equals A162956 convolved with (1, 3, 3, 3, ...).

Original entry on oeis.org

1, 4, 10, 19, 25, 40, 67, 94, 100, 115, 142, 175, 208, 280, 388, 469, 475, 490, 517, 550, 583, 655, 763, 850, 883, 955, 1069, 1201, 1372, 1696, 2101, 2344, 2350, 2365, 2392, 2425, 2458, 2530, 2638, 2725, 2758, 2830, 2944, 3076, 3247, 3571, 3976, 4225, 4258
Offset: 1

Views

Author

Gary W. Adamson, Jul 18 2009

Keywords

Comments

Can be considered a toothpick sequence for N=3, following rules analogous to those in A160552 (= special case of "A"), A151548 = special case "B", and the toothpick sequence A139250 (N=2) = special case "C".
To obtain the infinite set of toothpick sequences, (N = 2, 3, 4, ...), replace the multiplier "2" in A160552 with any N, getting a triangle with 2^n terms. Convolve this A sequence with (1, N, 0, 0, 0, ...) = B such that row terms of A triangles converge to B.
Then generalized toothpick sequences (C) = A convolved with (1, N, N, N, ...).
Examples: A160552 * (1, 2, 0, 0, 0,...) = a B-type sequence A151548.
A160552 * (1, 2, 2, 2, 2,...) = the toothpick sequence A139250 for N=2.
A162956 is analogous to A160552 but replaces "2" with the multiplier "3".
Row terms of A162956 tend to A162957 = (1, 3, 0, 0, 0, ...) * A162956.
Toothpick sequence for N = 3 = A162958 = A162956 * (1, 3, 3, 3, ...).
Row sums of "A"-type triangles = powers of (N+2); since row sums of A160552 = (1, 4, 16, 64, ...), while row sums of A162956 = (1, 5, 25, 125, ...).
Is there an illustration of this sequence using toothpicks? - Omar E. Pol, Dec 13 2016

Crossrefs

Third diagonal of A163311.

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<2, n,
          (j-> 3*b(j)+b(j+1))(n-2^ilog2(n)))
        end:
    a:= proc(n) option remember;
          `if`(n=0, 0, a(n-1)+2*b(n-1)+b(n))
        end:
    seq(a(n), n=1..100);  # Alois P. Heinz, Jan 28 2017
  • Mathematica
    b[n_] := b[n] = If[n<2, n, Function[j, 3*b[j]+b[j+1]][n-2^Floor[Log[2, n]] ]];
    a[n_] := a[n] = If[n == 0, 0, a[n-1] + 2*b[n-1] + b[n]];
    Array[a, 100] (* Jean-François Alcover, Jun 11 2018, after Alois P. Heinz *)

Extensions

Clarified definition by Omar E. Pol, Feb 06 2017

A113679 Expansion of (1-x-2x^2)/(1-x).

Original entry on oeis.org

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

Views

Author

Paul Barry, Nov 04 2005

Keywords

Comments

From Gary W. Adamson, Mar 06 2012: (Start)
Signed (1, 0, -2, 2, -2, 2, ...) and convolved with the Toothpick sequence A139250 = A151548: (1, 3, 5, 7, 5, 11, ...). The inverse of (1, 0, -2, 2, -2, ...) = A151575: (1, 0, 2, -2, 6, -10, 22, ...).
The unsigned sequence convolved with:
(1, 2, 3, ...) = A002523, (n^2 + 1). Convolved with:
(A001045) = .... A097064: (1, 1, 5, 9, 21, 41, ...).
(End)

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(1-x-2x^2)/(1-x),{x,0,80}],x] (* or *) Join[{1,0}, PadRight[{},80,-2]] (* Harvey P. Dale, Mar 05 2012 *)

Formula

a(n) = C(0, n) + 2*C(1, n) - 2.

A162957 A162956 convolved with (1, 3, 0, 0, 0, ...).

Original entry on oeis.org

1, 4, 7, 13, 7, 19, 34, 40, 7, 19, 34, 46, 40, 91, 142, 121, 7, 19, 34, 46, 40, 91, 142, 127, 40, 91, 148, 178, 211, 415, 547, 364, 7, 19, 34, 46, 40, 91, 142, 127, 40, 91, 148, 178, 211, 415, 547, 370, 40, 91, 148, 178, 211, 415, 553, 421, 211, 421, 622, 745, 1048, 1792, 2005, 1093
Offset: 1

Views

Author

Gary W. Adamson, Jul 18 2009

Keywords

Comments

Rows of A162956 tend to this sequence. Analogous to rows of A160552 tending to A151548.

Crossrefs

Formula

Equals (1, 3, 0, 0, 0, ...) * (1, 1, 4, 1, 4, 7, 13, 1, 4, 7, 13, 7, 19, 34, 40, ...).

Extensions

a(20), a(21) corrected and more terms from Georg Fischer, Jul 17 2025

A255045 a(n) = (1 + A160552(n))/2.

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 4, 1, 2, 3, 4, 3, 6, 9, 8, 1, 2, 3, 4, 3, 6, 9, 8, 3, 6, 9, 10, 11, 20, 25, 16, 1, 2, 3, 4, 3, 6, 9, 8, 3, 6, 9, 10, 11, 20, 25, 16, 3, 6, 9, 10, 11, 20, 25, 18, 11, 20, 27, 30, 41, 64, 65, 32, 1, 2, 3, 4, 3, 6, 9, 8, 3, 6, 9, 10, 11, 20, 25, 16, 3, 6, 9, 10, 11, 20, 25, 18, 11, 20, 27, 30, 41, 64, 65, 32, 3, 6, 9, 10, 11, 20, 25, 18
Offset: 1

Views

Author

Omar E. Pol, Feb 13 2015

Keywords

Comments

Triangle of numbers related to cellular automata.
It appears that this is also a triangle read by rows in which row n lists the first 2^(n-1) terms of A255046, with n >= 1.

Examples

			Written as an irregular triangle in which the length of row j is 2^j, j >= 0, the sequence begins:
1;
1,2;
1,2,3,4;
1,2,3,4,3,6,9,8;
1,2,3,4,3,6,9,8,3,6,9,10,11,20,25,16;
1,2,3,4,3,6,9,8,3,6,9,10,11,20,25,16,3,6,9,10,11,20,25,18,11,20,27,30,41,64,65,32;
...
It appears that the right border gives A000079.
It appears that the row sums give A007582.
It appears that rows converge to A255046.
		

Crossrefs

Previous Showing 11-15 of 15 results.