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 1-6 of 6 results.

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

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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

A327971 Bitwise XOR of trajectories of rule 30 and its mirror image, rule 86, when both are started from a lone 1 cell: a(n) = A110240(n) XOR A265281(n).

Original entry on oeis.org

0, 0, 10, 20, 130, 396, 2842, 4420, 38610, 124220, 684490, 1385044, 8891330, 26281036, 192525274, 269101060, 2454365330, 8588410876, 43860512138, 89059958420, 551714970626, 1663794165260, 12235920695450, 19683098342340, 164315052318034, 538162708968636, 2894532467106378, 6192136868790228, 37503903254935874, 114926395086966988, 814341599153559130
Offset: 0

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Author

Antti Karttunen, Oct 03 2019

Keywords

Comments

Each term is a binary palindrome when its trailing zeros (in base 2) are omitted, that is, a term of A057890.
Compare the binary string illustrations drawn for the first 1024 terms of this sequence and for A327976, which has almost the same definition.

Crossrefs

Cf. A003987, A030101, A057890, A110240, A265281, A280508, A328106 (binary weight of terms).
Cf. also A327972, A327973, A327976, A328103, A328104 for other such combinations.

Programs

Formula

a(n) = A110240(n) XOR A265281(n).
a(n) = A280508(A110240(n)) = A110240(n) XOR A030101(A110240(n)).
a(n) = A280508(A265281(n)) = A265281(n) XOR A030101(A265281(n)).
For n >= 1, a(n) = (1/2) * (A327973(n-1) XOR A327976(n-1)).

A328105 Binary weight of A328104: a(n) = A000120(A110240(n) OR 2*A110240(n)).

Original entry on oeis.org

2, 4, 5, 8, 7, 12, 9, 15, 11, 17, 17, 20, 19, 26, 21, 29, 22, 27, 30, 33, 30, 34, 37, 40, 37, 39, 41, 49, 44, 49, 48, 53, 41, 56, 49, 64, 50, 62, 59, 66, 64, 60, 66, 69, 61, 77, 65, 73, 67, 74, 70, 89, 78, 87, 78, 94, 85, 88, 89, 100, 91, 101, 95, 110, 92, 85, 98, 102, 102, 102, 115, 109, 101, 105, 121, 118, 121, 129
Offset: 0

Views

Author

Antti Karttunen, Oct 05 2019

Keywords

Crossrefs

Programs

Formula

For all n >= 0, A070952(a) < a(n) <= 2*A070952(n).

A328107 Binary weight of A327973.

Original entry on oeis.org

2, 4, 5, 6, 7, 8, 9, 13, 11, 13, 13, 14, 17, 18, 19, 23, 20, 23, 24, 27, 26, 24, 23, 30, 31, 29, 29, 31, 36, 35, 36, 37, 35, 34, 35, 42, 40, 46, 41, 50, 54, 48, 52, 47, 47, 53, 47, 51, 51, 54, 48, 51, 60, 55, 56, 64, 61, 60, 59, 68, 71, 67, 65, 78, 64, 63, 68, 72, 70, 74, 79, 89, 85, 77, 85, 76, 79, 83, 78, 90, 97, 82, 87, 81
Offset: 1

Views

Author

Antti Karttunen, Oct 05 2019

Keywords

Crossrefs

Programs

Formula

a(n) = A000120(A327973(n)) = A000120(A110240(n) XOR 2*A110240(n-1)).

A328108 Binary weight of A327976.

Original entry on oeis.org

2, 4, 3, 6, 5, 12, 7, 11, 9, 13, 7, 12, 13, 20, 15, 23, 16, 19, 22, 25, 20, 28, 19, 30, 29, 39, 27, 29, 32, 37, 32, 37, 29, 38, 37, 38, 36, 44, 47, 44, 42, 46, 42, 53, 41, 49, 53, 47, 45, 58, 52, 55, 56, 65, 66, 60, 67, 56, 61, 64, 63, 77, 59, 66, 60, 67, 72, 72, 64, 84, 57, 81, 63, 79, 67, 92, 77, 77, 74, 80, 81, 88, 77
Offset: 1

Views

Author

Antti Karttunen, Oct 05 2019

Keywords

Crossrefs

Programs

Formula

a(n) = A000120(A327976(n)).
a(n) = A000120(A110240(n) XOR 2*A265281(n-1)).
a(n) = A000120(A110240(n) XOR 2*A030101(A110240(n-1))).

A328109 Binary weight of A328103: a(n) = A000120(A110240(n) XOR A267357(n)).

Original entry on oeis.org

0, 1, 4, 3, 5, 6, 8, 10, 9, 11, 11, 14, 14, 13, 16, 11, 18, 16, 17, 25, 18, 21, 25, 24, 22, 30, 25, 28, 30, 26, 33, 34, 36, 34, 33, 37, 37, 44, 38, 44, 51, 38, 43, 48, 45, 57, 38, 47, 50, 52, 49, 61, 53, 56, 63, 58, 56, 54, 60, 59, 64, 54, 60, 66, 69, 60, 67, 69, 72, 68, 75, 74, 77, 68, 78, 76, 75, 78, 72, 81, 80, 91, 78
Offset: 0

Views

Author

Antti Karttunen, Oct 05 2019

Keywords

Crossrefs

Programs

Formula

a(n) = A000120(A328103(n)) = A000120(A110240(n) XOR A267357(n)).
Showing 1-6 of 6 results.