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 1-10 of 12 results. Next

A269175 a(n) = number of distinct k for which A269174(k) = n; number of finite predecessors for pattern encoded in the binary expansion of n in Wolfram's Rule 124 cellular automaton.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Feb 22 2016

Keywords

Comments

At positions A000225 seems to occur the record values of this sequence: 1, 0, 1, 1, 1, 2, 2, 3, 4, 5, 7, 9, 12, 16, 21, 28, 37, 49, 65, 86, 114, 151, 200, 265, 351, 465, ... which seem to match with A000931 (Padovan sequence), or more exactly, with A182097 (Number of compositions (ordered partitions) into parts 2 and 3). Note that these values give also the number of predecessors for each "repunit-pattern" (2^n)-1 in Rule 110 cellular automaton, as rules 110 and 124 are mirror images of each other.

Crossrefs

Cf. A269176 (indices of zeros), A269177 (of nonzeros), A269178 (of ones).

Programs

  • Scheme
    (definec (A269175 n) (let loop ((p 0) (s 0)) (cond ((> p n) s) (else (loop (+ 1 p) (+ s (if (= n (A269174 p)) 1 0))))))) ;; Very straightforward and very slow.
    ;; Somewhat optimized version:
    (definec (A269175 n) (if (zero? n) 1 (let ((nwid-1 (- (A000523 n) 1))) (let loop ((p (if (< n 2) 0 (A000079 nwid-1))) (s 0)) (cond ((> (A000523 p) nwid-1) s) (else (loop (+ 1 p) (+ s (if (= n (A269174 p)) 1 0)))))))))

A269176 Numbers not present in A269174; indices of zeros in A269175.

Original entry on oeis.org

1, 2, 4, 5, 8, 9, 10, 13, 16, 17, 18, 20, 21, 23, 25, 26, 29, 32, 33, 34, 36, 37, 39, 40, 41, 42, 43, 45, 46, 49, 50, 52, 53, 57, 58, 61, 64, 65, 66, 68, 69, 71, 72, 73, 74, 75, 77, 78, 80, 81, 82, 83, 84, 85, 86, 87, 89, 90, 92, 93, 97, 98, 100, 101, 104, 105, 106, 109, 113, 114, 116, 117, 121, 122, 125, 128, 129
Offset: 1

Views

Author

Antti Karttunen, Feb 22 2016

Keywords

Comments

Numbers n for which there is no any k such that A269174(k) = n.
These are binary representations (shown in decimal) of Garden of Eden patterns in Wolfram's Rule 124 cellular automaton if infinite predecessors are forbidden.

Crossrefs

Cf. A269177 (complement).

A332465 Numbers n for which A269174(sigma(n)) is equal to 2*A269174(n).

Original entry on oeis.org

6, 28, 348, 496, 732, 886, 2924, 3573, 4972, 5448, 7544, 8128, 23388, 54842, 66928, 89200, 92296, 109786, 118064, 121552, 349512, 356488, 367472, 550432, 634784, 839984, 842452, 1234048, 1561408, 1797496, 2154584, 2364832, 2788808, 2927992, 3451456, 3585328, 5952364, 5991852, 6687136, 8238752, 10594336, 11210712, 11261020
Offset: 1

Views

Author

Antti Karttunen, Feb 16 2020

Keywords

Comments

Numbers n such that A332464(n) is equal to A269174(2*n).
There are only three odd terms <= 2^32 among the first 113 terms of this sequence: 3573, 29255157, 936109557. Because A269174 preserves the 2-adic valuation of its argument, all such odd terms are of the form 4m+1, and must be present in A191218. Incidentally, these three terms are also present in A228058, but not in A332227.
See from the graph how unevenly the terms appear. Compare also the scatter plots of A269174 and A332464, also of a similar sequence A332445.

Examples

			          k   factorization        sigma(k)     A269174(sigma(k)) = A269174(2*k)
        348 = 2^2 * 3 * 29         840          2008,
       3573 = 3^2 * 397            5174         15486,
   29255157 = 3^2 * 3250573        42257462     126737534,
  936109557 = 3^2 * 104012173      1352158262   4055424126.
		

Crossrefs

Cf. A000396 (a subsequence).

Programs

  • Mathematica
    b[n_] := BitAnd[BitOr[n, 2n], BitOr[BitXor[n, 2n], BitXor[n, 4n]]];
    okQ[n_] := b[DivisorSigma[1, n]] == 2 b[n];
    Reap[For[n = 1, n <= 12*10^6, n++, If[okQ[n], Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Feb 23 2020 *)
  • PARI
    A269174(n) = bitand(bitor(n,n<<1),bitor(bitxor(n,n<<1),bitxor(n,n<<2)));
    isA332465(n) = (A269174(sigma(n))==2*A269174(n));

A328103 Bitwise XOR of trajectories of rule 30 and rule 124, when both are started from a lone 1 cell: a(n) = A110240(n) XOR A267357(n).

Original entry on oeis.org

0, 4, 30, 100, 398, 1748, 6510, 28628, 102590, 456132, 1642078, 7289764, 26336590, 116802708, 420215854, 1865678868, 6741198206, 29904470916, 107568473246, 477629808612, 1725756768270, 7655529847380, 27537572248046, 122273029571156, 441793665700414, 1959816793456452, 7049616389341662, 31301899019407908, 113099196716630990, 501713069953322004
Offset: 0

Views

Author

Antti Karttunen, Oct 05 2019

Keywords

Crossrefs

Cf. A003987, A110240, A267357, A269160, A269174, A328109 (binary weight of terms).
Cf. also A327971, A327972, A327973, A327976, A328104 for other such combinations, and also A328111.

Programs

Formula

a(n) = A110240(n) XOR A267357(n), where XOR is bitwise exclusive or (A003987).

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)).

A161903 Convert n into a sequence of binary digits, apply one step of the rule 110 cellular automaton, and interpret the results as a binary integer.

Original entry on oeis.org

0, 3, 6, 7, 12, 15, 14, 13, 24, 27, 30, 31, 28, 31, 26, 25, 48, 51, 54, 55, 60, 63, 62, 61, 56, 59, 62, 63, 52, 55, 50, 49, 96, 99, 102, 103, 108, 111, 110, 109, 120, 123, 126, 127, 124, 127, 122, 121, 112, 115, 118, 119, 124, 127, 126, 125, 104, 107, 110, 111, 100, 103, 98, 97, 192, 195, 198, 199, 204, 207, 206, 205, 216, 219, 222, 223, 220, 223, 218, 217, 240, 243, 246, 247, 252, 255, 254, 253, 248, 251, 254, 255, 244, 247, 242, 241, 224, 227, 230, 231, 236
Offset: 0

Views

Author

Ben Branman, Jan 30 2011

Keywords

Comments

a(a(a(...1))) (n times) gives A006978(n)

Examples

			For n=19, the evolution after one step is
0, 1, 0, 0, 1, 1  (n=19)
1, 1, 0, 1, 1, 1  (a(n)=55)
So a(n)=55.
		

Crossrefs

Programs

  • Mathematica
    a[n_] :=
    FromDigits[
      Drop[Part[CellularAutomaton[110, {IntegerDigits[n, 2], 0}], 1], -1],
       2];Table[a[n],{n,0,100}]

Formula

a(n) = A057889(A269174(A057889(n))). - Antti Karttunen, Jun 02 2018

A269177 Numbers that have a finite predecessor in Wolfram's Rule 124 cellular automaton; numbers n for which A269175(n) > 0.

Original entry on oeis.org

0, 3, 6, 7, 11, 12, 14, 15, 19, 22, 24, 27, 28, 30, 31, 35, 38, 44, 47, 48, 51, 54, 55, 56, 59, 60, 62, 63, 67, 70, 76, 79, 88, 91, 94, 95, 96, 99, 102, 103, 107, 108, 110, 111, 112, 115, 118, 119, 120, 123, 124, 126, 127, 131, 134, 140, 143, 152, 155, 158, 159, 176, 179, 182, 183, 187, 188, 190, 191, 192, 195
Offset: 0

Views

Author

Antti Karttunen, Feb 22 2016

Keywords

Comments

Sequence A269174 sorted into ascending order with duplicates removed.
The indexing starts from zero, because a(0) = 0 is a special case in this sequence. (Zero is the only number which is its own predecessor).

Crossrefs

Cf. A269176 (complement).
Cf. A269178 (a subsequence).

A269178 Numbers that have a unique finite predecessor in Wolfram's Rule 124 cellular automaton; numbers n for which A269175(n) = 1.

Original entry on oeis.org

0, 3, 6, 7, 11, 12, 14, 15, 19, 22, 24, 27, 28, 30, 35, 38, 44, 47, 48, 51, 54, 55, 56, 60, 67, 70, 76, 79, 88, 91, 94, 95, 96, 99, 102, 103, 107, 108, 110, 111, 112, 119, 120, 131, 134, 140, 143, 152, 155, 158, 159, 176, 179, 182, 183, 187, 188, 190, 191, 192, 195, 198, 199, 203, 204, 206, 207, 211, 214, 216, 219
Offset: 0

Views

Author

Antti Karttunen, Feb 22 2016

Keywords

Comments

The indexing starts from zero, because a(0) = 0 is a special case in this sequence. (Zero is the only number which is its own predecessor).

Crossrefs

Subsequence of A269177.

A269173 Formula for Wolfram's Rule 126 cellular automaton: a(n) = (n XOR 2n) OR (n XOR 4n).

Original entry on oeis.org

0, 7, 14, 15, 28, 31, 30, 27, 56, 63, 62, 63, 60, 63, 54, 51, 112, 119, 126, 127, 124, 127, 126, 123, 120, 127, 126, 127, 108, 111, 102, 99, 224, 231, 238, 239, 252, 255, 254, 251, 248, 255, 254, 255, 252, 255, 246, 243, 240, 247, 254, 255, 252, 255, 254, 251, 216, 223, 222, 223, 204, 207, 198, 195, 448, 455, 462
Offset: 0

Views

Author

Antti Karttunen, Feb 22 2016

Keywords

Examples

			a(4) = (4 XOR 2*4) OR (4 XOR 4*4) = 12 OR 20 = 28. - _Indranil Ghosh_, Apr 02 2017
		

Crossrefs

Cf. A267365 (iterates starting from 1).
Cf. A269174.

Programs

  • C
    #include 
    int main()
    {
        int n;
        for(n=0; n<=100; n++){
            printf("%d, ",(n^(2*n))|(n^(4*n)));
        }
        return 0;
    } /* Indranil Ghosh, Apr 02 2017 */
  • Mathematica
    Table[BitOr[BitXor[n, 2n], BitXor[n, 4n]], {n, 0, 100}] (* Indranil Ghosh, Apr 02 2017 *)
  • PARI
    for(n=0, 100, print1(bitor(bitxor(n, 2*n), bitxor(n, 4*n)),", ")) \\ Indranil Ghosh, Apr 02 2017
    
  • Python
    print([(n^(2*n))|(n^(4*n)) for n in range(101)]) # Indranil Ghosh, Apr 02 2017
    
  • Scheme
    (define (A269173 n) (A003986bi (A048724 n) (A048725 n)))
    

Formula

a(n) = A048724(n) OR A048725(n) = (n XOR 2n) OR (n XOR 4n), where OR is a bitwise-or (A003986) and XOR is A003987.
Other identities. For all n >= 0:
a(2*n) = 2*a(n).
a(n) = A057889(a(A057889(n))). [Rule 126 is amphichiral (symmetric).]

A328111 a(n) = A080069(n) OR A267357(n).

Original entry on oeis.org

1, 3, 15, 47, 191, 743, 2935, 12015, 47615, 190363, 737255, 3092431, 11777535, 48562151, 194672615, 778681963, 3117668351, 12677730147, 49850341191, 192901085003, 795560607711, 3243899871031, 12977889600367, 51055599708139, 204124618746111, 791262494980483, 3318011560984519, 12661179187462123, 52138250822737375, 212591566440951715, 836346216751952367, 3236342451194541807
Offset: 0

Views

Author

Antti Karttunen, Oct 05 2019

Keywords

Comments

The pattern has a remarkably nice texture. A269174 gives the trajectory of 1-D Cellular Automaton rule 124 (which is a mirror image of rule 110), when started from a single alive cell. Trails of its evolution can be dimly discerned on the right hand side of given illustrations, while the left hand side shows the evolution of (left hand side of) iterated Dyck-path system A080069 unblemished.

Crossrefs

Cf. A080069, A080070, and also A079438 and A123050.
Cf. also A328103.

Formula

a(n) = A080069(n) OR A267357(n), where OR is bitwise-OR, A003986.
Showing 1-10 of 12 results. Next