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 1-4 of 4 results.

A267111 Permutation of natural numbers: a(1) = 1, a(A087686(n)) = 2*a(n-1), a(A088359(n)) = 1+2*a(n), where A088359 and A087686 = numbers that occur only once (resp. more than once) in A004001, the Hofstadter-Conway $10000 sequence.

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 6, 8, 9, 11, 15, 10, 13, 14, 12, 16, 17, 19, 23, 31, 18, 21, 27, 22, 29, 30, 20, 25, 26, 28, 24, 32, 33, 35, 39, 47, 63, 34, 37, 43, 55, 38, 45, 59, 46, 61, 62, 36, 41, 51, 42, 53, 54, 44, 57, 58, 60, 40, 49, 50, 52, 56, 48, 64, 65, 67, 71, 79, 95, 127, 66, 69, 75, 87, 111, 70, 77, 91, 119, 78, 93, 123
Offset: 1

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Author

Antti Karttunen, Jan 10 2016

Keywords

Crossrefs

Inverse: A267112.
Similar or related permutations: A006068, A054429, A276441, A233275, A233277, A276343, A276345, A276445.
Cf. also permutations A266411, A266412 and arrays A265901, A265903.

Formula

a(1) = 1; for n > 1, if A093879(n-1) = 0 [when n is in A087686], a(n) = 2*a(A080677(n)-1), otherwise [when n is in A088359], a(n) = 1 + 2*a(A004001(n)-1).
Equally, for n > 1, if A093879(n-1) = 0, a(n) = 2*a(n - A004001(n)), otherwise a(n) = 1 + 2*a(A004001(n)-1). [Above formula in a more symmetric form.]
As a composition of other permutations:
a(n) = A054429(A276441(n)).
a(n) = A233275(A276343(n)).
a(n) = A233277(A276345(n)).
a(n) = A006068(A276445(n)).
Other identities. For all n >= 0:
a(2^n) = 2^n. [Follows from the properties (3) and (4) of A004001 given on page 227 of Kubo & Vakil paper.]

A265332 a(n) is the index of the column in A265901 where n appears; also the index of the row in A265903 where n appears.

Original entry on oeis.org

1, 2, 1, 3, 1, 1, 2, 4, 1, 1, 1, 2, 1, 2, 3, 5, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 6, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 2, 3, 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 4, 5, 7, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 2, 3, 1, 1, 1, 2, 1, 1, 2, 1, 2, 3, 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 4
Offset: 1

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Author

Antti Karttunen, Jan 09 2016

Keywords

Comments

If all 1's are deleted, the remaining terms are the sequence incremented. - after Franklin T. Adams-Watters Oct 05 2006 comment in A051135.
Ordinal transform of A162598.

Examples

			Illustration how the sequence can be constructed by concatenating the frequency counts Q_n of each successive level n of A004001-tree:
--
             1                                      Q_0 = (1)
             |
            _2__                                    Q_1 = (2)
           /    \
         _3    __4_____                             Q_2 = (1,3)
        /     /  |     \
      _5    _6  _7    __8___________                Q_3 = (1,1,2,4)
     /     /   / |   /  |  \        \
   _9    10  11 12  13  14  15___    16_________    Q_4 = (1,1,1,2,1,2,3,5)
  /     /   /  / |  /  / |   |\  \   | \  \  \  \
17    18  19 20 21 22 23 24 25 26 27 28 29 30 31 32
--
The above illustration copied from the page 229 of Kubo and Vakil paper (page 5 in PDF).
		

Crossrefs

Essentially same as A051135 apart from the initial term, which here is set as a(1)=1.
Cf. A162598 (corresponding other index).
Cf. A265754.
Cf. also A267108, A267109, A267110.

Programs

  • Mathematica
    terms = 120;
    h[1] = 1; h[2] = 1;
    h[n_] := h[n] = h[h[n - 1]] + h[n - h[n - 1]];
    seq[nmax_] := seq[nmax] = (Length /@ Split[Sort @ Array[h, nmax, 2]])[[;; terms]];
    seq[nmax = 2 terms];
    seq[nmax += terms];
    While[seq[nmax] != seq[nmax - terms], nmax += terms];
    seq[nmax] (* Jean-François Alcover, Dec 19 2021 *)
  • Scheme
    (define (A265332 n) (if (= 1 n) 1 (A051135 n)))

Formula

a(1) = 1; for n > 1, a(n) = A051135(n).

A267110 If A051135(n) = 1, then a(n) = A004001(n) - 1, otherwise a(n) = n - A004001(n).

Original entry on oeis.org

0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 6, 5, 7, 6, 7, 8, 8, 9, 10, 11, 9, 12, 13, 10, 14, 11, 12, 15, 13, 14, 15, 16, 16, 17, 18, 19, 20, 17, 21, 22, 23, 18, 24, 25, 19, 26, 20, 21, 27, 28, 22, 29, 23, 24, 30, 25, 26, 27, 31, 28, 29, 30, 31, 32, 32, 33, 34, 35, 36, 37, 33, 38, 39, 40, 41, 34, 42, 43, 44, 35, 45, 46, 36, 47
Offset: 1

Views

Author

Antti Karttunen, Jan 16 2016

Keywords

Comments

For n > 1, a(n) gives the contents of the parent of the node which contains n in A267112-tree.
Each n > 0 occurs exactly twice, in positions A088359(n) and A087686(n+1).
The sequence maps each n > 1 to a number which is one digit shorter in binary system (cf. "Other identities"). This follows because A004001 is monotonic and A004001(2^n) = 2^(n-1) (see properties (2) and (3) given on page 227 of Kubo & Vakil paper, or page 3 in PDF), and also how the frequency counts Q_n for A004001 are recursively constructed (see Kubo & Vakil paper, p. 229 or A265332 for the illustration).

Crossrefs

Programs

Formula

If A051135(n) = 1 [Equally: if A265332(n) = 1], then a(n) = A004001(n) - 1, otherwise a(n) = n - A004001(n).
Other identities. For all n >= 2:
A070939(a(n)) = A070939(n) - 1. [See Comments section.]

A267108 a(n) = A000120(A267111(n)).

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 2, 1, 2, 3, 4, 2, 3, 3, 2, 1, 2, 3, 4, 5, 2, 3, 4, 3, 4, 4, 2, 3, 3, 3, 2, 1, 2, 3, 4, 5, 6, 2, 3, 4, 5, 3, 4, 5, 4, 5, 5, 2, 3, 4, 3, 4, 4, 3, 4, 4, 4, 2, 3, 3, 3, 3, 2, 1, 2, 3, 4, 5, 6, 7, 2, 3, 4, 5, 6, 3, 4, 5, 6, 4, 5, 6, 5, 6, 6, 2, 3, 4, 5, 3, 4, 5, 4, 5, 5, 3, 4, 5, 4, 5, 5, 4, 5, 5, 5, 2, 3, 4, 3, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 4
Offset: 1

Views

Author

Antti Karttunen, Jan 16 2016

Keywords

Crossrefs

Formula

a(1) = 1; for n > 1, if A265332(n) = 1 [when n is one of the terms of A088359], a(n) = 1 + a(A004001(n)-1), otherwise a(n) = a(n-A004001(n)).
a(n) = A000120(A267111(n)).
Other identities. For all n >= 1:
a(n) = A070939(n) - A267109(n).
Showing 1-4 of 4 results.