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.

Showing 1-8 of 8 results.

A071043 Number of 0's in n-th row of triangle in A071029.

Original entry on oeis.org

0, 0, 3, 1, 7, 5, 9, 3, 15, 13, 17, 11, 21, 15, 21, 7, 31, 29, 33, 27, 37, 31, 37, 23, 45, 39, 45, 31, 49, 35, 45, 15, 63, 61, 65, 59, 69, 63, 69, 55, 77, 71, 77, 63, 81, 67, 77, 47, 93, 87, 93, 79, 97, 83, 93, 63, 105, 91, 101, 71, 105, 75, 93, 31, 127, 125, 129
Offset: 0

Views

Author

Hans Havermann, May 26 2002

Keywords

References

  • S. Wolfram, A New Kind of Science, Wolfram Media, 2002; Chapter 3.

A071049 Number of 1's in n-th generation of 1-D CA using Rule 110, started with a single 1.

Original entry on oeis.org

1, 2, 3, 3, 5, 3, 5, 6, 8, 5, 6, 8, 8, 8, 11, 11, 13, 9, 11, 11, 13, 14, 16, 14, 14, 13, 13, 17, 22, 20, 16, 17, 24, 19, 14, 19, 25, 18, 20, 25, 24, 19, 24, 31, 27, 26, 24, 22, 32, 31, 28, 24, 29, 34, 30, 31, 37, 34, 34, 36, 35, 34, 35, 36, 43, 40, 36, 38, 37, 39, 40
Offset: 0

Views

Author

Hans Havermann, May 26 2002

Keywords

Comments

Number of 1's in n-th row of triangle in A070887.
Although the initial behavior is chaotic, it is an astonishing fact, pointed out by Wolfram [2002, p. 39], that after about three thousand terms all the irregularities disappear. - N. J. A. Sloane, May 15 2015

References

  • Matthew Cook, A Concrete View of Rule 110 Computation, in "The Complexity of Simple Programs", T. Neary, D. Woods, A. K. Seda, and N. Murphy (Eds.), 2008, pp. 31-55.
  • S. Wolfram, A New Kind of Science, Wolfram Media, 2002; Chapter 3.

Crossrefs

Programs

Formula

For n >= 2854, a(n+469) = -a(n+453) + a(n+256) + a(n+240) + a(n+229) + a(n+213) - a(n+16) - a(n). - N. J. A. Sloane, May 15 2015

Extensions

Added references and links. - N. J. A. Sloane, Aug 09 2014
Changed offset to make consistent with A070952, etc. - N. J. A. Sloane, Aug 15 2014

A071044 Number of ON cells at generation n of 1-D CA defined by Rule 22, starting with a single ON cell.

Original entry on oeis.org

1, 3, 2, 6, 2, 6, 4, 12, 2, 6, 4, 12, 4, 12, 8, 24, 2, 6, 4, 12, 4, 12, 8, 24, 4, 12, 8, 24, 8, 24, 16, 48, 2, 6, 4, 12, 4, 12, 8, 24, 4, 12, 8, 24, 8, 24, 16, 48, 4, 12, 8, 24, 8, 24, 16, 48, 8, 24, 16, 48, 16, 48, 32, 96, 2, 6, 4, 12, 4, 12, 8, 24, 4, 12, 8, 24, 8, 24, 16, 48
Offset: 0

Views

Author

Hans Havermann, May 26 2002

Keywords

Comments

Number of 1's in n-th row of triangle in A071029.

Examples

			From _Michael De Vlieger_, Oct 05 2015: (Start)
First 8 rows, replacing "0" with "." for better visibility of ON cells, total of ON cells in each row to the left of the diagram:
1                  1
3                1 1 1
2              1 . . . 1
6            1 1 1 . 1 1 1
2          1 . . . . . . . 1
6        1 1 1 . . . . . 1 1 1
4      1 . . . 1 . . . 1 . . . 1
12   1 1 1 . 1 1 1 . 1 1 1 . 1 1 1
2  1 . . . . . . . . . . . . . . . 1
(End)
		

References

  • S. Wolfram, A New Kind of Science, Wolfram Media, 2002; Chapter 3.

Crossrefs

Cf. A071029.

Programs

  • Mathematica
    ArrayPlot[CellularAutomaton[22, {{1}, 0}, 20]] (* N. J. A. Sloane, Aug 15 2014 *)
    Total /@ CellularAutomaton[22, {{1}, 0}, 80] (* Michael De Vlieger, Oct 05 2015 *)

Formula

If the binary expansion of n is b_{r-1} b_{r-2} ... b_2 b_1 b_0, then a(n) = 3^b_0 * Prod_{i=1..r-1} 2^b_i = 2^wt(n) if n is even, or (3/2)*2^wt(n) if n is odd (cf. A000120). - N. J. A. Sloane, Aug 09 2014
G.f. = (1+3*x)*Prod_{k >= 1} (1+2*x^(2^k)). - N. J. A. Sloane, Aug 09 2014

Extensions

Better description from N. J. A. Sloane, Aug 15 2014

A292686 Sierpinski-type iteration: start with a(0)=1, at each step, replace 0 with 000 and 1 with 101.

Original entry on oeis.org

1, 101, 101000101, 101000101000000000101000101, 101000101000000000101000101000000000000000000000000000101000101000000000101000101
Offset: 0

Views

Author

M. F. Hasler, Oct 20 2017

Keywords

Comments

See A292687 for the decimal representation of a(n) viewed as a "binary number", i.e., as written in base 2.
The Sierpinski carpet (A153490) can be seen as 2-dimensional version of this 1-dimensional variant. The classical Sierpinski gasket triangle (Pascal's triangle mod 2) and "Rule 18" (or Rule 90, A070886) and "Rule 22" (A071029) have similar graphs.
The n-th term a(n) has 3^n digits, the middle third of which are all zero. The digits of a(n) are again the first and last 3^n digits of a(n+1), separated by 3^n zeros.

Examples

			a(0) = 1 -> 101 = a(1);
a(1) = 101 -> concat(101,000,101) = 101000101 = a(2).
		

Crossrefs

Cf. A292687 for the decimal representation of a(n) viewed as a "binary number", i.e., as written in base 2.
Cf. A153490 (Sierpinski carpet), A047999 (Sierpinski gasket = Pascal's triangle mod 2), A070886 (Rule 18 / Rule 90), A071029 (Rule 22).
Cf. A088917.

Programs

  • Mathematica
    A292686[nmax_]:=FoldList[Times,1,100^(3^Range[0,nmax-1])+1];A292686[5] (* Paolo Xausa, May 13 2023 *)
  • PARI
    a(n,a=1)=for(k=1,n,a=fromdigits(binary(a)*5,8));fromdigits(binary(a),10) \\ Illustration of the first formula.
    
  • PARI
    A292686(n)=prod(k=0,n-1,100^(3^k)+1)

Formula

a(n+1) = convert(5*a(n), from base 8, to base 2).
a(n+1) = (100^(3^n)+1)*a(n).
a(n) = Product_{k=0 .. n-1} (100^(3^k)+1).

A266382 Decimal representation of the n-th iteration of the "Rule 22" elementary cellular automaton starting with a single ON (black) cell.

Original entry on oeis.org

1, 7, 17, 119, 257, 1799, 4369, 30583, 65537, 458759, 1114129, 7798903, 16843009, 117901063, 286331153, 2004318071, 4294967297, 30064771079, 73014444049, 511101108343, 1103806595329, 7726646167303, 18764712120593, 131352984844151, 281479271743489
Offset: 0

Views

Author

Robert Price, Dec 28 2015

Keywords

Comments

Empirical observation: This sequence can also be generated in Conway's Game of Life by setting the initial condition to be an infinite row of ON cells in both directions. After each iteration, rows of cells turned ON will be labeled as 1 and rows that are OFF will be labeled 0. When the resulting binary number is converted to decimal notation, the resulting sequence is the same as A266382. [Brook Estifanos, Mar 09 2016]

References

  • S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.

Crossrefs

Cf. A071029.

Programs

  • Mathematica
    rule=22; rows=30; ca=CellularAutomaton[rule,{{1},0},rows-1,{All,All}]; (* Start with single black cell *) catri=Table[Take[ca[[k]],{rows-k+1,rows+k-1}],{k,1,rows}]; (* Truncated list of each row *) Table[FromDigits[catri[[k]],2],{k,1,rows}] (* Decimal Representation of Rows *)

A266381 Binary representation of the n-th iteration of the "Rule 22" elementary cellular automaton starting with a single ON (black) cell.

Original entry on oeis.org

1, 111, 10001, 1110111, 100000001, 11100000111, 1000100010001, 111011101110111, 10000000000000001, 1110000000000000111, 100010000000000010001, 11101110000000001110111, 1000000010000000100000001, 111000001110000011100000111, 10001000100010001000100010001
Offset: 0

Views

Author

Robert Price, Dec 28 2015

Keywords

References

  • S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.

Crossrefs

Cf. A071029.

Programs

  • Mathematica
    rule=22; rows=20; ca=CellularAutomaton[rule,{{1},0},rows-1,{All,All}]; (* Start with single black cell *) catri=Table[Take[ca[[k]],{rows-k+1,rows+k-1}],{k,1,rows}]; (* Truncated list of each row *) Table[FromDigits[catri[[k]]],{k,1,rows}] (* Binary Representation of Rows *)

A266383 Total number of ON (black) cells after n iterations of the "Rule 22" elementary cellular automaton starting with a single ON (black) cell.

Original entry on oeis.org

1, 4, 6, 12, 14, 20, 24, 36, 38, 44, 48, 60, 64, 76, 84, 108, 110, 116, 120, 132, 136, 148, 156, 180, 184, 196, 204, 228, 236, 260, 276, 324, 326, 332, 336, 348, 352, 364, 372, 396, 400, 412, 420, 444, 452, 476, 492, 540, 544, 556, 564, 588, 596, 620, 636
Offset: 0

Views

Author

Robert Price, Dec 28 2015

Keywords

References

  • S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.

Crossrefs

Cf. A071029.

Programs

  • Mathematica
    rule=22; rows=60; ca=CellularAutomaton[rule,{{1},0},rows-1,{All,All}]; (* Start with single black cell *) catri=Table[Take[ca[[k]],{rows-k+1,rows+k-1}],{k,1,rows}]; (* Truncated list of each row *) nbc=Table[Total[catri[[k]]],{k,1,rows}]; (* Number of Black cells in stage n *) Table[Total[Take[nbc,k]],{k,1,rows}] (* Number of Black cells through stage n *)

A266384 Total number of OFF (white) cells after n iterations of the "Rule 22" elementary cellular automaton starting with a single ON (black) cell.

Original entry on oeis.org

0, 0, 3, 4, 11, 16, 25, 28, 43, 56, 73, 84, 105, 120, 141, 148, 179, 208, 241, 268, 305, 336, 373, 396, 441, 480, 525, 556, 605, 640, 685, 700, 763, 824, 889, 948, 1017, 1080, 1149, 1204, 1281, 1352, 1429, 1492, 1573, 1640, 1717, 1764, 1857, 1944, 2037, 2116
Offset: 0

Views

Author

Robert Price, Dec 28 2015

Keywords

References

  • S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.

Crossrefs

Cf. A071029.

Programs

  • Mathematica
    rule = 22; rows = 60; ca = CellularAutomaton[rule, {{1}, 0}, rows - 1, {All, All}]; (* Start with single black cell *) catri = Table[Take[ca[[k]], {rows - k + 1, rows + k - 1}], {k, 1, rows}]; (* Truncated list of each row *) nbc =
    Table[Total[catri[[k]]], {k, 1, rows}]; (* Number of Black cells in stage n *) nwc = Table[Length[catri[[k]]] - nbc[[k]], {k, 1, rows}]; (* Number of White cells in stage n *) Table[Total[Take[nwc, k]], {k, 1, rows}] (* Number of White cells through stage n *)
Showing 1-8 of 8 results.