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 1-9 of 9 results.

A100054 Records in A100053.

Original entry on oeis.org

0, 2, 3, 4, 5, 6, 8, 9, 11, 14, 15, 23, 24, 26, 28, 33, 35
Offset: 0

Views

Author

Eric W. Weisstein, Oct 31 2004

Keywords

Crossrefs

Programs

  • Mathematica
    clip[lst_] := Block[{p = Flatten@ Position[lst, 1]}, Take[lst, {Min@ p, Max@ p}]]; t = Max /@ Map[Length@ # &, Map[Split@ # &, Map[clip, CellularAutomaton[30, {{1}, 0}, 5000]]] /. 1 -> Nothing, {2}]; a = {0}; Do[If[t[[n]] > Max@ a, AppendTo[a, t[[n]]]], {n, Length@ t}]; a (* Michael De Vlieger, Oct 06 2015 *)

A100055 Where records occur in A100053.

Original entry on oeis.org

0, 2, 4, 6, 8, 16, 32, 43, 46, 64, 128, 256, 512, 1024, 2048, 4096, 8192
Offset: 0

Views

Author

Eric W. Weisstein, Nov 01 2004

Keywords

Crossrefs

A110240 Decimal form of binary integer produced by the ON cells at n-th generation following Wolfram's Rule 30 cellular automaton starting from a single ON-cell represented as 1.

Original entry on oeis.org

1, 7, 25, 111, 401, 1783, 6409, 28479, 102849, 456263, 1641433, 7287855, 26332369, 116815671, 420186569, 1865727615, 6741246849, 29904391303, 107568396185, 477630335215, 1725755276049, 7655529137527, 27537575631497
Offset: 0

Views

Author

Keywords

Comments

See A245549 for binary equivalents. See A070952 for number of ON cells. - N. J. A. Sloane, Jul 28 2014
For n > 0: 3 < a(n+1) / a(n) < 5, floor(a(n+1)/a(n)) = A010702(n+1). - Reinhard Zumkeller, Jun 08 2013
Iterates of A269160 starting from a(0) = 1. See also A269168. - Antti Karttunen, Feb 20 2016
Also, the decimal representation of the n-th generation of the "Rule 66847740" 5-neighbors elementary cellular automaton starting with a single ON (black) cell. - Philipp O. Tsvetkov, Jul 17 2019

Examples

			a(1)=1 because the automaton begins at first "generation" with one black cell: 1;
a(2)=5 because one black cell, through Rule 30 at 2nd generation, produces three contiguous black cells: 111 (binary), so 7 (decimal);
a(3)=25 because the third generation is "black black white white black" cells: 11001, so 25 (decimal).
		

Crossrefs

Cf. A030101, A070950, A051023, A092539, A092540, A070952 (number of ON cells, the binary weight of terms), A100053, A100054, A100055, A094603, A094604, A000225, A074890, A010702, A245549, A269160, A269162.
Cf. A269165 (indices of ones in this sequence).
Cf. A269166 (a left inverse).
Left edge of A269168.
Cf. also A265281, A328106.
For bitwise XOR (and OR) combinations with other such 1D CA trajectories, see for example: A327971, A327972, A327973, A327976, A328103, A328104.

Programs

  • Haskell
    a110240 = foldl (\v d -> 2 * v + d) 0 . map toInteger . a070950_row
    -- Reinhard Zumkeller, Jun 08 2013
    
  • Mathematica
    rows = 23; ca = CellularAutomaton[30, {{1}, 0}, rows-1]; Table[ FromDigits[ ca[[k, rows-k+1 ;; rows+k-1]], 2], {k, 1, rows}] (* Jean-François Alcover, Jun 07 2012 *)
  • PARI
    A269160(n) = bitxor(n, bitor(2*n, 4*n));
    A110240(n) = if(!n,1,A269160(A110240(n-1))); \\ Antti Karttunen, Oct 05 2019
    
  • Python
    def A269160(n): return(n^((n<<1)|(n<<2)))
    def genA110240():
        '''Yield successive terms of A110240 (Rule 30) starting from A110240(0)=1.'''
        s = 1
        while True:
           yield s
           s = A269160(s)
    def take(n, g):
        '''Returns a list composed of the next n elements returned by generator g.'''
        z = []
        if 0 == n: return(z)
        for x in g:
            z.append(x)
            if n > 1: n = n-1
            else: return(z)
    take(30, genA110240())
    # Antti Karttunen, Oct 05 2019
  • Scheme
    ;; With memoization-macro definec.
    (definec (A110240 n) (if (zero? n) 1 (A269160 (A110240 (- n 1)))))
    ;; Antti Karttunen, Feb 20 2016
    

Formula

From Antti Karttunen, Feb 20 2016: (Start)
a(0) = 1, for n >= 1, a(n) = A269160(a(n-1)).
a(n) = A030101(A265281(n)). [The rule 30 is the mirror image of the rule 86.]
A269166(a(n)) = n for all n >= 0. (End)
From Antti Karttunen, Oct 05 2019: (Start)
For n >= 1, a(n) = a(n-1) XOR 2*A328104(n-1).
For n >= 1, a(n) = 2*a(n-1) XOR A327973(n). (End)

Extensions

More terms from Eric W. Weisstein, Apr 08 2006
Offset corrected by Reinhard Zumkeller, Jun 08 2013

A110267 Total number of black cells at the first n generations of a single black cell following Wolfram's Rule 30 cellular automaton.

Original entry on oeis.org

1, 4, 7, 13, 17, 26, 31, 43, 50, 62, 73, 87, 99, 118, 131, 153, 168, 187, 207, 231, 252, 275, 298, 326, 352, 379, 405, 438, 468, 502, 533, 572, 598, 637, 666, 712, 744, 788, 826, 871, 918, 959, 1004, 1053, 1091, 1146, 1188, 1239, 1283, 1336, 1379, 1438, 1490
Offset: 0

Views

Author

Alexandre Wajnberg, Sep 06 2005

Keywords

Comments

At each generation, "looking back", one can see "behind", groups of black cells: total number of black cells (cumulative sum of first n terms of A070952).

Examples

			a(1)=1 because one black cell;
a(2)=4 because there are now 3 contiguous black cell connected to the first one, which form one only black surface of 4 cells;
a(3)=7 because appear three black cells: 4+3=7
From _Michael De Vlieger_, Dec 16 2015: (Start)
First 12 rows, replacing "0" with "." for better visibility of ON cells, followed by the total number of ON cells per row, and the running total up to that row:
                1                  =  1 ->   1
              1 1 1                =  3 ->   4
            1 1 . . 1              =  3 ->   7
          1 1 . 1 1 1 1            =  6 ->  13
        1 1 . . 1 . . . 1          =  4 ->  17
      1 1 . 1 1 1 1 . 1 1 1        =  9 ->  26
    1 1 . . 1 . . . . 1 . . 1      =  5 ->  31
  1 1 . 1 1 1 1 . . 1 1 1 1 1 1    = 12 ->  43
1 1 . . 1 . . . 1 1 1 . . . . . 1  =  7 ->  50
(End)
		

Crossrefs

See A265704 for an essentially identical sequence.

Programs

  • Haskell
    a110267 n = a110267_list !! (n-1)
    a110267_list = scanl1 (+) a070952_list
    -- Reinhard Zumkeller, Jun 08 2013
  • Mathematica
    Accumulate[Total /@ CellularAutomaton[30, {{1}, 0}, 52]] (* Michael De Vlieger, Dec 16 2015 *)

Extensions

Offset changed by Reinhard Zumkeller, Jun 08 2013

A317530 a(n) is that generation of the rule-30 1D cellular automaton started from a single ON cell in which n successive OFF cells appears for the first time.

Original entry on oeis.org

4, 3, 5, 7, 9, 17, 45, 33, 44, 67, 47, 66, 130, 65, 129, 517, 260, 516, 259, 515, 258, 514, 257, 513, 4101, 1025, 4100, 2049, 4099, 16388, 4098, 16387, 4097, 16386, 8193, 16385, 262150, 32769, 262149, 65537, 262148, 131073, 262147, 524291, 262146, 524290, 262145, 524289
Offset: 1

Views

Author

Philipp O. Tsvetkov, Jul 30 2018

Keywords

Comments

OFF cells outside the triangle of active cells are ignored.
This is also the position at which n appears for the first time in A100053.

Examples

			The Rule-30 1D cellular automaton started from a single ON (.) cell generates the following triangle:
1                          .
2                        . . .
3                      . . 0 0 .
4                    . . 0 . . . .
5                  . . 0 0 . 0 0 0 .
6                . . 0 . . . . 0 . . .
7              . . 0 0 . 0 0 0 0 . 0 0 .
8            . . 0 . . . . 0 0 . . . . . .
9          . . 0 0 . 0 0 0 . . . 0 0 0 0 0 .
10       . . 0 . . . . 0 . . 0 0 . 0 0 0 . . .
11     . . 0 0 . 0 0 0 0 . 0 . . . . 0 . . 0 0 .
12   . . 0 . . . . 0 0 . . 0 . 0 0 0 0 . 0 . . . .
13 . . 0 0 . 0 0 0 . . . 0 0 . . 0 0 . . 0 . 0 0 0 .
1 OFF cell (0) appears for the first time in generation (line) 4, thus a(1) = 4;
2 consecutive OFF cells (00) appear for the first time in generation (line) 3, thus a(2) = 3;
5 consecutive OFF cells (00000) appear for the first time in generation (line) 9, thus a(5) = 9;
...
		

Crossrefs

Cf. A100053.

Programs

  • C
    See Links section.
  • Mathematica
    CellularAutomaton[30, {{1}, 0}, 10000];
    (Reverse[Internal`DeleteTrailingZeros[
          Reverse[Internal`DeleteTrailingZeros[#]]]]) & /@ %;
    Table[Position[(Max@FoldList[If[#2 == 0, #1 + 1, 0] &, 0, #]) & /@ %, i] //
       Flatten // First, {i, 1, 29}]

Extensions

a(30)-a(36) from Robert G. Wilson v, Aug 07 2018
Data corrected and more terms from Rémy Sigrist, Jul 06 2020

A319610 a(n) is the minimal number of successive OFF cells that appears in n-th generation of rule-30 1D cellular automaton started from a single ON cell.

Original entry on oeis.org

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

Views

Author

Philipp O. Tsvetkov, Sep 24 2018

Keywords

Comments

OFF cells outside the triangle of active cells are ignored.

Examples

			The Rule-30 1D cellular automaton started from a single ON (.) cell generates the following triangle:
1                          .                             a(1)= (0)
2                        . . .                           a(2)= (0)
3                      . . 0 0 .                         a(3)= (2)
4                    . . 0 . . . .                       a(4)= (1)
5                  . . 0 0 . 0 0 0 .                     a(5)= (2)
6                . . 0 . . . . 0 . . .                   a(6)= (1)
7              . . 0 0 . 0 0 0 0 . 0 0 .                 a(7)= (2)
8            . . 0 . . . . 0 0 . . . . . .               a(8)= (1)
9          . . 0 0 . 0 0 0 . . . 0 0 0 0 0 .             a(9)= (2)
10       . . 0 . . . . 0 . . 0 0 . 0 0 0 . . .           a(10)=(1)
11     . . 0 0 . 0 0 0 0 . 0 . . . . 0 . . 0 0 .         a(11)=(1)
12   . . 0 . . . . 0 0 . . 0 . 0 0 0 0 . 0 . . . .       a(12)=(1)
13 . . 0 0 . 0 0 0 . . . 0 0 . . 0 0 . . 0 . 0 0 0 .     a(13)=(1)
		

Crossrefs

Cf. A100053.

Programs

  • Mathematica
    CellularAutomaton[30, {{1}, 0}, 200];
    (Reverse[Internal`DeleteTrailingZeros[Reverse[Internal`DeleteTrailingZeros[#]]]]) & /@ %;
    Table[Length /@ Select[%[[i]] // Split, Total[#] == 0 &] // Min, {i, 1, % // Length}]

Formula

G.f.: x (x + x/(1 - x) + x^3 + x^5 + x^7) (conjectured).
For n > 9, a(n)=1 at least up to n = 20000.
It is conjectured that for all n>=10, a(n)=1.
A period-4 pattern of length-1 runs starting at row 26 forces a(n) = 1 for all n >= 26 (see image). - Charlie Neder, Dec 15 2018

A110266 Number of blocks of ON cells in n-th row of triangle generated by Wolfram's "Rule 30".

Original entry on oeis.org

1, 1, 2, 2, 3, 3, 4, 3, 4, 5, 6, 6, 7, 7, 8, 7, 7, 8, 10, 9, 9, 11, 14, 12, 11, 12, 15, 16, 14, 15, 17, 14, 15, 17, 20, 18, 18, 18, 21, 21, 17, 19, 21, 20, 23, 22, 23, 22, 23, 21, 27, 30, 26, 27, 29, 29, 28, 28, 33, 31, 30, 31, 36, 32, 28, 29, 33, 33, 33, 35
Offset: 1

Views

Author

Alexandre Wajnberg, Sep 06 2005

Keywords

Comments

Old name was "Number of trees appearing at n-th generation of a black cell following Wolfram's Rule 30 cellular automaton."
At each generation, "looking back", one can see "behind", groups (sort of black isles) of contiguous black cells which after a while appear to be trees growing. It should be possible to describe each one of them in terms of trees theory.

Examples

			a(1)=1 because one black cell;
a(2)=1 because there are now 3 contiguous black cell connected to the first one, which forms one only black surface;
a(3)=2 because two black cells are now connected to the preceding black surface and another black cell appears, which is isolated, so we have two separate black surfaces: 2.
From _Charlie Neder_, Feb 06 2019: (Start)
Rule 30 triangle begins:
                     1
                    111
                   11  1
                  11 1111
                 11  1   1
                11 1111 111
               11  1    1  1
              11 1111  111111
             11  1   111     1
and the number of blocks of ON cells in each row is 1, 1, 2, 2, 3, 3, 4, 3, 4, ... (End)
		

Crossrefs

Extensions

New name and a(17)-a(70) from Charlie Neder, Feb 06 2019

A319658 a(n) is the minimal number of successive ON cells that appears in n-th generation of rule-30 1D cellular automaton started from a single ON cell.

Original entry on oeis.org

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

Views

Author

Philipp O. Tsvetkov, Sep 25 2018

Keywords

Examples

			The Rule-30 1D cellular automaton started from a single ON (.) cell generates the following triangle:
1                          .                             a(1)= (1)
2                        . . .                           a(2)= (3)
3                      . . 0 0 .                         a(3)= (1)
4                    . . 0 . . . .                       a(4)= (2)
5                  . . 0 0 . 0 0 0 .                     a(5)= (1)
6                . . 0 . . . . 0 . . .                   a(6)= (2)
7              . . 0 0 . 0 0 0 0 . 0 0 .                 a(7)= (1)
8            . . 0 . . . . 0 0 . . . . . .               a(8)= (2)
9          . . 0 0 . 0 0 0 . . . 0 0 0 0 0 .             a(9)= (1)
10       . . 0 . . . . 0 . . 0 0 . 0 0 0 . . .           a(10)=(1)
11     . . 0 0 . 0 0 0 0 . 0 . . . . 0 . . 0 0 .         a(11)=(1)
12   . . 0 . . . . 0 0 . . 0 . 0 0 0 0 . 0 . . . .       a(12)=(1)
13 . . 0 0 . 0 0 0 . . . 0 0 . . 0 0 . . 0 . 0 0 0 .     a(13)=(1)
		

Crossrefs

Programs

  • Mathematica
    CellularAutomaton[30, {{1}, 0}, 100];
    (Reverse[Internal`DeleteTrailingZeros[
          Reverse[Internal`DeleteTrailingZeros[#]]]]) & /@ %;
    Table[Length /@ Select[%[[i]] // Split, Total[#] > 0 &] // Min, {i,
      1, % // Length}]

Formula

G.f.: 1/(1 - x) + 2 x + x^3 + x^5 + x^7 + x^13 (conjectured).
For n > 14, a(n)=1 at least until n = 10000.
It is conjectured that for all n >= 15, a(n)=1.
A period-4 pattern of length-1 runs beginning on row 19 forces a(n) = 1 for all n >= 19 (see image). - Charlie Neder, Dec 15 2018

A319611 a(n) is the number of gaps in the n-th generation of the rule-30 1D cellular automaton started from a single ON.

Original entry on oeis.org

0, 0, 1, 1, 2, 2, 3, 2, 3, 4, 5, 5, 6, 6, 7, 6, 6, 7, 9, 8, 8, 10, 13, 11, 10, 11, 14, 15, 13, 14, 16, 13, 14, 16, 19, 17, 17, 17, 20, 20, 16, 18, 20, 19, 22, 21, 22, 21, 22, 20, 26, 29, 25, 26, 28, 28, 27, 27, 32, 30, 29, 30, 35, 31, 27, 28, 32, 32, 32, 34, 37, 30, 27, 36, 37, 39, 42, 41, 43, 41, 34
Offset: 0

Views

Author

Philipp O. Tsvetkov, Sep 24 2018

Keywords

Comments

OFF cells outside the triangle of active cells are ignored.

Examples

			The Rule-30 1D cellular automaton started from a single ON (.) cell generates the following triangle:
1                          .                             a(1)= (0)
2                        . . .                           a(2)= (0)
3                      . . 0 0 .                         a(3)= (1)
4                    . . 0 . . . .                       a(4)= (1)
5                  . . 0 0 . 0 0 0 .                     a(5)= (2)
6                . . 0 . . . . 0 . . .                   a(6)= (2)
7              . . 0 0 . 0 0 0 0 . 0 0 .                 a(7)= (3)
8            . . 0 . . . . 0 0 . . . . . .               a(8)= (2)
9          . . 0 0 . 0 0 0 . . . 0 0 0 0 0 .             a(9)= (3)
10       . . 0 . . . . 0 . . 0 0 . 0 0 0 . . .           a(10)=(4)
11     . . 0 0 . 0 0 0 0 . 0 . . . . 0 . . 0 0 .         a(11)=(5)
12   . . 0 . . . . 0 0 . . 0 . 0 0 0 0 . 0 . . . .       a(12)=(5)
13 . . 0 0 . 0 0 0 . . . 0 0 . . 0 0 . . 0 . 0 0 0 .     a(13)=(6)
		

Crossrefs

Cf. A100053.

Programs

  • Mathematica
    CellularAutomaton[30, {{1}, 0}, 200];
    (Reverse[Internal`DeleteTrailingZeros[
          Reverse[Internal`DeleteTrailingZeros[#]]]]) & /@ %;
    Table[
    Length /@ Select[%[[i]] // Split, Total[#] == 0 &] // Length,
    {i, 1, % // Length}
    ]
Showing 1-9 of 9 results.