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.

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A136036 a(n) = A063882(n+1) - A063882(n).

Original entry on oeis.org

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

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Author

Reinhard Zumkeller, Dec 11 2007

Keywords

Comments

0 <= a(n) <= 1; 1 <= a(n)+a(n+1)+a(n+2) <= 2 for n>5.

Crossrefs

Cf. A063882.

A132173 Maternal generation number of A063882(n).

Original entry on oeis.org

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

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Author

N. J. A. Sloane, Nov 07 2007

Keywords

A278055 Relative of Hofstadter Q-sequence: a(1) = 1, a(2) = 2, a(3) = 3, a(4) = 4, a(5) = 5; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 5.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 9, 10, 11, 12, 12, 13, 14, 15, 15, 16, 17, 17, 18, 18, 19, 20, 21, 21, 22, 23, 24, 24, 25, 26, 26, 27, 27, 28, 29, 30, 30, 31, 32, 33, 33, 34, 35, 35, 36, 36, 37, 38, 39, 39, 40, 41, 42, 42, 43, 44, 44, 45, 45, 46, 47, 48, 48, 49, 50, 50, 51
Offset: 1

Views

Author

Nathan Fox, Nov 10 2016

Keywords

Comments

This sequence is monotonic, with successive terms increasing by 0 or 1. So the sequence hits every positive integer.
A number k appears twice in this sequence if and only if for some i, k is congruent to A057198(i) mod 3^i and k > A057198(i).

Crossrefs

Programs

  • Mathematica
    a[n_] := a[n] = a[n - a[n -1]] + a[n - a[n -2]] + a[n - a[n -3]]; a[1] = 1; a[2] = 2; a[3] = 3; a[4] = 4; a[5] = 5; Array[a, 71] (* Robert G. Wilson v, Dec 02 2016 *)
  • PARI
    A=Vecsmall([]);
    a(n)=if(n<7, return(n)); if(#ACharles R Greathouse IV, Nov 19 2016

Formula

a(n) ~ 2n/3.

A063892 a(1) = a(2) = a(3) = 1, a(n) = a(n-a(n-2))+a(n-a(n-3)) for n>3.

Original entry on oeis.org

1, 1, 1, 2, 4, 6, 5, 3, 3, 9, 6, 4, 7, 12, 9, 5, 7, 10, 16, 16, 10, 12, 12, 16, 14, 21, 13, 17, 8, 14, 24, 26, 19, 12, 8, 23, 22, 23, 12, 17, 18, 28, 35, 26, 16, 22, 34, 47, 22, 6, 10, 36, 69, 36
Offset: 1

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Author

Henry Bottomley, Aug 29 2001

Keywords

Comments

Undefined for n>54 since a(53)=69>=55.

Examples

			a(7) = a(7-a(5))+a(7-a(4)) = a(7-4)+a(7-2) = a(3)+a(5) = 1+4 = 5.
		

Crossrefs

See A064714 for a variant which does not die.

Programs

  • Maple
    #Q(r,s) with initial values 1,1,1,..., from N. J. A. Sloane, Apr 15 2014
    r:=2; s:=3;
    a:=proc(n) option remember; global r,s;
    if n <= s then 1
    else
        if (a(n-r) <= n) and (a(n-s) <= n) then
        a(n-a(n-r))+a(n-a(n-s));
        else lprint("died with n =",n); return (-1);
        fi;
    fi; end;
    [seq(a(n),n=1..54)];

A087777 a(1) = ... = a(4) = 1; a(n) = a(n - a(n-2)) + a(n - a(n-4)).

Original entry on oeis.org

1, 1, 1, 1, 2, 4, 6, 7, 7, 5, 3, 8, 9, 11, 12, 9, 9, 13, 11, 9, 13, 16, 13, 19, 16, 11, 14, 16, 21, 22, 14, 14, 19, 17, 22, 27, 25, 16, 20, 28, 22, 22, 26, 25, 24, 32, 26, 22, 29, 29, 32, 35, 32, 27, 26, 34, 30, 33, 40, 25, 27, 46, 40, 33, 32, 28, 36, 50, 44, 31, 36, 38, 46, 53, 41, 29, 41
Offset: 1

Views

Author

Roger L. Bagula, Oct 05 2003

Keywords

Comments

This is the sequence Q(2,4) in the Hofstadter-Huber classification.
It is not known if this sequence is defined for all positive n. Balamohan et al. comment that it shows "inscrutably wild behavior".

Crossrefs

Cf. A005185 (Q(1,2)), A063882 (Q(1,4)), A046700.

Programs

  • Magma
    [n le 4 select 1 else Self(n-Self(n-2))+Self(n-Self(n-4)): n in [1..80]]; // Vincenzo Librandi, Sep 10 2016
  • Maple
    a := proc(n) option remember; if n<=4 then 1 else if n > a(n-2) and n > a(n-4) then RETURN(a(n-a(n-2))+a(n-a(n-4))); else ERROR(" died at n= ", n); fi; fi; end;
  • Mathematica
    a[n_] := a[n] = If[n <= 4, 1, a[n - a[n - 2]] + a[n - a[n - 4]]];
    Array[a, 80] (* Jean-François Alcover, Nov 24 2017 *)

Extensions

Edited by N. J. A. Sloane, Nov 06 2007

A285757 a(n) = a(n - a(n - 2)) + a(n - a(n - 8)), with a(i) = i for 1 <= i <= 9.

Original entry on oeis.org

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

Views

Author

Nathan Fox, Apr 25 2017

Keywords

Comments

The sequence a(n) is monotonic, with successive terms increasing by 0 or 1. So the sequence hits every positive integer.
This sequence can be obtained from A063882 using a construction of Isgur et al.

Crossrefs

Programs

  • Maple
    A285757:=proc(n) option remember: if n <= 0 then 0: elif n = 1 then 1: elif n = 2 then 2: elif n = 3 then 3: elif n = 4 then 4: elif n = 5 then 5: elif n = 6 then 6: elif n = 7 then 7: elif n = 8 then 8: elif n = 9 then 9: else A285757(n-A285757(n-2)) + A285757(n-A285757(n-8)): fi: end:

A285758 A slow relative of Hofstadter's Q sequence.

Original entry on oeis.org

1, 2, 2, 2, 2, 2, 2, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 11, 12, 12, 12, 13, 14, 15, 16, 16, 16, 17, 18, 18, 18, 19, 20, 21, 22, 22, 22, 22, 22, 23, 24, 24, 24, 25, 26, 27, 28, 28, 28, 29, 30, 30, 30, 31, 32, 33, 34, 34, 34, 34, 34, 35, 36
Offset: 1

Views

Author

Nathan Fox, Apr 25 2017

Keywords

Comments

a(n) is the solution to the recurrence relation a(n) = a(n-a(n-2)) + a(n-a(n-8)), with the initial conditions: a(1) = 1, a(i) = 2 for 2 <= i <= 8, and a(9) = 3.
The sequence a(n) is monotonic, with successive terms increasing by 0 or 1. So the sequence hits every positive integer.
This sequence can be obtained from A063882 using a construction of Isgur et al.

Crossrefs

Programs

  • Maple
    A285758:=proc(n) option remember: if n <= 0 then 0: elif n = 1 then 1: elif n = 2 then 2: elif n = 3 then 2: elif n = 4 then 2: elif n = 5 then 2: elif n = 6 then 2: elif n = 7 then 2: elif n = 8 then 2: elif n = 9 then 3: else A285758(n-A285758(n-2)) + A285758(n-A285758(n-8)): fi: end:

A285759 a(n) = a(n - 1 - a(n - 1)) + a(n - 1 - a(n - 4)), with a(1) = 1, a(2) = 1, a(3) = 1, a(4) = 2.

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 3, 4, 5, 5, 5, 6, 6, 7, 8, 8, 9, 9, 10, 10, 10, 11, 11, 12, 13, 13, 14, 14, 15, 15, 16, 17, 17, 17, 18, 18, 19, 19, 20, 20, 20, 21, 21, 22, 23, 23, 24, 24, 25, 25, 26, 27, 27, 27, 28, 28, 29, 29, 30, 31, 31, 32, 32, 33
Offset: 1

Views

Author

Nathan Fox, Apr 25 2017

Keywords

Comments

The sequence a(n) is monotonic, with successive terms increasing by 0 or 1. So the sequence hits every positive integer.

Crossrefs

Programs

  • Maple
    A285759:=proc(n) option remember: if n <= 0 then 0: elif n = 1 then 1: elif n = 2 then 1: elif n = 3 then 1: elif n = 4 then 2: else A285759(n-1-A285759(n-1)) + A285759(n-1-A285759(n-4)): fi: end:

A285760 a(n) = a(n - 2 - a(n - 1)) + a(n - 2 - a(n - 4)), with a(1) = 1, a(2) = 1, a(3) = 2, a(4) = 2.

Original entry on oeis.org

1, 1, 2, 2, 2, 3, 3, 4, 4, 4, 5, 5, 6, 7, 7, 7, 8, 8, 8, 9, 9, 10, 11, 11, 12, 12, 13, 13, 14, 14, 14, 15, 15, 16, 16, 16, 17, 17, 18, 19, 19, 20, 20, 21, 21, 22, 23, 23, 23, 24, 24, 25, 25, 26, 27, 27, 27, 28, 28, 28, 29, 29, 30, 31, 31
Offset: 1

Views

Author

Nathan Fox, Apr 25 2017

Keywords

Comments

The sequence a(n) is monotonic, with successive terms increasing by 0 or 1. So the sequence hits every positive integer.

Crossrefs

Programs

  • Maple
    A285760:=proc(n) option remember: if n <= 0 then 0: elif n = 1 then 1: elif n = 2 then 1: elif n = 3 then 2: elif n = 4 then 2: else A285760(n-2-A285760(n-1)) + A285760(n-2-A285760(n-4)): fi: end:

A285761 A slow relative of Hofstadter's Q sequence.

Original entry on oeis.org

1, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 8, 8, 8, 9, 9, 10, 10, 10, 11, 11, 12, 12, 12, 13, 13, 14, 15, 15, 15, 16, 16, 16, 17, 17, 18, 19, 19, 19, 20, 20, 20, 21, 21, 22, 23, 23, 23, 24, 24, 24, 25, 25, 26, 27, 27, 28, 28, 29, 29
Offset: 1

Views

Author

Nathan Fox, Apr 25 2017

Keywords

Comments

a(n) is the solution to the recurrence relation a(n) = a(n-4-a(n-1)) + a(n-4-a(n-4)), with the initial conditions: a(1) = 1, a(2) = 2, a(3) = a(4) = a(5) = 3, a(6) = a(7) = a(8) = 4, a(9) = a(10) = 5.
The sequence a(n) is monotonic, with successive terms increasing by 0 or 1. So the sequence hits every positive integer.

Crossrefs

Programs

  • Maple
    A285761:=proc(n) option remember: if n <= 0 then 0: elif n = 1 then 1: elif n = 2 then 2: elif n = 3 then 3: elif n = 4 then 3: elif n = 5 then 3: elif n = 6 then 4: elif n = 7 then 4: elif n = 8 then 4: elif n = 9 then 5: elif n = 10 then 5: else A285761(n-4-A285761(n-1)) + A285761(n-4-A285761(n-4)): fi: end:
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