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.

Previous Showing 11-19 of 19 results.

A163900 Squared distance between n's location in A054238 array and A163357 array.

Original entry on oeis.org

0, 0, 1, 1, 8, 18, 5, 5, 4, 2, 9, 5, 2, 2, 9, 9, 0, 2, 1, 1, 0, 0, 1, 1, 4, 4, 9, 1, 2, 4, 5, 9, 16, 10, 25, 17, 16, 16, 25, 9, 36, 36, 49, 25, 10, 4, 5, 1, 10, 18, 5, 5, 10, 16, 17, 25, 10, 20, 25, 29, 36, 36, 25, 49, 128, 162, 113, 113, 128, 128, 113, 145, 100, 100, 89, 113, 162
Offset: 0

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Author

Antti Karttunen, Sep 19 2009

Keywords

Crossrefs

Positions of zeros: A163901. See also A163898, A163899.

Formula

a(n) = A000290(abs(A059906(n)-A059252(n))) + A000290(abs(A059905(n)-A059253(n))).

A163539 The change in Y-coordinate when moving from the n-1:th to the n-th term in the type I Hilbert's Hamiltonian walk A163357.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 01 2009

Keywords

Crossrefs

These are the first differences of A059252. See also: A163538, A163541, A163543.

Formula

a(0)=0, a(n) = A059252(n) - A059252(n-1).

A165466 Squared distance between n's location in A163334 array and A163359 array.

Original entry on oeis.org

0, 2, 2, 2, 2, 10, 10, 2, 0, 0, 2, 10, 20, 10, 10, 18, 32, 32, 50, 74, 100, 100, 72, 50, 32, 50, 50, 34, 20, 20, 16, 16, 16, 10, 4, 4, 2, 4, 8, 8, 8, 10, 20, 18, 20, 20, 26, 50, 50, 40, 20, 20, 20, 20, 32, 32, 34, 40, 58, 74, 100, 74, 74, 80, 80, 80, 52, 52, 50, 34, 34, 32
Offset: 0

Views

Author

Antti Karttunen, Oct 06 2009

Keywords

Comments

Equivalently, squared distance between n's location in A163336 array and A163357 array. See example at A166043.

Crossrefs

Positions of zeros: A165467. See also A166043, A165464, A163897, A163900.

Formula

a(n) = A000290(abs(A163529(n)-A059253(n))) + A000290(abs(A163528(n)-A059252(n))).

A165464 Squared distance between n's location in A163334 array and A163357 array.

Original entry on oeis.org

0, 0, 2, 4, 2, 4, 2, 0, 0, 2, 2, 4, 4, 4, 2, 0, 0, 2, 2, 4, 4, 2, 0, 0, 0, 0, 2, 4, 4, 2, 8, 10, 16, 16, 4, 2, 2, 10, 16, 10, 8, 8, 20, 20, 20, 18, 18, 32, 18, 10, 4, 2, 4, 10, 8, 2, 2, 10, 10, 4, 4, 4, 2, 10, 16, 26, 20, 10, 2, 4, 10, 18, 32, 32, 50, 52, 52, 34, 40, 58, 80, 80, 106, 146
Offset: 0

Views

Author

Antti Karttunen, Oct 06 2009

Keywords

Comments

Equivalently, squared distance between n's location in A163336 array and A163359 array. See example at A166041.

Crossrefs

Positions of zeros: A165465. See also A165466, A163897, A163900.

Formula

a(n) = A000290(abs(A163529(n)-A059252(n))) + A000290(abs(A163528(n)-A059253(n))).

A275103 Hilbert curve constructed by greedy algorithm, such that each element is the smallest positive integer possible and that all rows, columns, and diagonals contain distinct numbers.

Original entry on oeis.org

1, 2, 3, 4, 2, 3, 1, 5, 4, 2, 5, 1, 2, 6, 5, 4, 3, 5, 1, 6, 7, 8, 9, 10, 6, 3, 4, 8, 7, 9, 8, 11, 2, 1, 8, 4, 1, 6, 10, 3, 9, 5, 7, 11, 3, 10, 6, 4, 9, 10, 1, 7, 11, 3, 9, 12, 4, 8, 5, 7, 11, 13, 12, 6
Offset: 0

Views

Author

Kerry Mitchell, Jul 16 2016

Keywords

Comments

The n-th cell has x-coordinates given by A059252 and y-coordinates given by A059253.
This idea is similar to A269526 and A274640, but for a different curve.

Examples

			The Hilbert curve begins:
  1,   4,   2,   3, ...
  2,   3,   5,   1, ...
  5,   6,   4,   2, ...
  4,   2,   1,   5, ...
...
		

Crossrefs

Cf. A269526 uses antidiagonals instead of the Hilbert curve and A274640 uses a square spiral.

A341019 a(n) is the Y-coordinate of the n-th point of the space filling curve M defined in Comments section; A341018 gives X-coordinates.

Original entry on oeis.org

0, 1, 0, 1, 2, 3, 4, 3, 4, 5, 6, 7, 6, 7, 6, 5, 4, 5, 6, 7, 6, 7, 6, 5, 4, 3, 4, 3, 2, 1, 0, 1, 0, 1, 2, 3, 2, 3, 2, 1, 0, 1, 0, 1, 2, 3, 4, 3, 4, 5, 4, 5, 6, 7, 8, 7, 8, 7, 6, 5, 6, 5, 6, 7, 8, 9, 10, 11, 10, 11, 10, 9, 8, 9, 8, 9, 10, 11, 12, 11, 12, 13, 12
Offset: 0

Views

Author

Rémy Sigrist, Feb 02 2021

Keywords

Comments

We define the family {M_n, n >= 0}, as follows:
- M_0 corresponds to the points (0, 0), (1, 1) and (2, 0), in that order:
+
/ \
/ \
+ +
O
- for any n >= 0, M_{n+1} is obtained by arranging 4 copies of M_n as follows:
+ . . . + . . . +
. B . B .
+ . . . + . . .
. B . .A C.A C.
. . --> + . . . + . . . +
.A C. .C . A.
+ . . . + . B.B .
O .A . C.
+ . . . + . . . +
O
- for any n >= 0, M_n has A087289(n) points,
- the space filling curve M is the limit of M_{2*n} as n tends to infinity.
The odd bisection of M is similar to a Hilbert's Hamiltonian walk (hence the connection with A059252).

Examples

			The curve M starts as follows:
       11+ 13+   +19 +21
        / \ / \ / \ / \
     10+ 12+ 14+18 +20 +22
        \     / \     /
        9+ 15+   +17 +23
        /     \ /     \
      8+  6+   +   +26 +24
        \ / \ 16  / \ /
        7+  5+   +27 +25
            /     \
          4+       +28
            \     /
        1+  3+   +29 +31
        / \ /     \ / \
      0+  2+       +30 +32
- so a(0) = a(2) = a(30) = a(32) = 0,
     a(1) = a(3) = a(29) = a(31) = 1.
		

Crossrefs

Programs

  • PARI
    See Links section.

Formula

A059252(n) = (a(2*n+1)-1)/2.
a(4*n) = 2*A341018(n).
a(16*n) = 4*a(n).

A341120 a(n) is the X-coordinate of the n-th point of the space filling curve C defined in Comments section; A341121 gives Y-coordinates.

Original entry on oeis.org

0, 0, 1, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 2, 1, 0, 0, 1, 1, 1, 0, 0, 1, 2, 2, 2, 3, 4, 4, 3, 3, 3, 4, 5, 5, 5, 4, 4, 5, 6, 6, 6, 7, 8, 8, 7, 7, 7, 8, 8, 7, 6, 6, 5, 5, 5, 6, 5, 5, 5, 6, 6, 7, 8, 8, 9, 9, 9, 8, 8, 9, 10, 10, 10, 11, 12, 12, 11, 11, 11, 12, 12, 13
Offset: 0

Views

Author

Kevin Ryde and Rémy Sigrist, Feb 05 2021

Keywords

Comments

We define the family {C_k, k >= 0}, as follows:
- C_0 corresponds to the points (0, 0), (0, 1), (1, 1), (2, 1) and (2, 0), in that order:
+---+---+
| |
+ +
O
- for any k >= 0, C_{k+1} is obtained by arranging 4 copies of C_k as follows:
+ . . . + . . . +
. B . B .
+ . . . + . . .
. B . .A C.A C.
. . --> + . . . + . . . +
.A C. .C . A.
+ . . . + . B.B .
O .A . C.
+ . . . + . . . +
O
- the space filling curve C is the limit of C_{2*k} as k tends to infinity.
The even bisection of the curve M defined in A341018 is similar to C and vice versa.
The third quadrisection of C is similar to the Hilbert Hamiltonian walk H = A059252, A059253.
H is the number of points in the middle of each unit square in Hilbert's subdivisions, whereas here points are at the starting corner of each unit square. This start is either the bottom left or top right corner depending on how many 180-degree rotations have been applied. These rotations are digit 3's of n written in base 4, hence the formula below adding A283316.

Examples

			Points n and their locations X=a(n), Y=A341121(n) begin as follows. n=7 and n=9 are both at X=3,Y=2, and n=11,n=31 both at X=3,Y=4.
      |       |
    4 | 16---17   12--11,31
      |  |         |    |
    3 | 15---14---13   10
      |                 |
    2 |            8---7,9
      |                 |
    1 |  1----2----3    6
      |  |         |    |
  Y=0 |  0         4----5
      +--------------------
       X=0    1    2    3
		

Crossrefs

Cf. A341121 (Y coordinate), A059285 (projection Y-X), A062880 (n on X=Y diagonal).

Programs

  • PARI
    See Links section.

Formula

a(n) = A341121(n) - A059285(n).
a(n) = A341121(n) iff n belongs to A062880.
a(2*n) = A341018(n).
a(4*n) = 2*A341121(n).
a(16*n) = 4*a(n).
a(n) = A059252(n) + A283316(n+1).
A059253(n) = (a(4*n+2)-1)/2.

A341121 a(n) is the Y-coordinate of the n-th point of the space filling curve C defined in Comments section; A341120 gives X-coordinates.

Original entry on oeis.org

0, 1, 1, 1, 0, 0, 1, 2, 2, 2, 3, 4, 4, 3, 3, 3, 4, 4, 5, 6, 6, 7, 7, 7, 6, 7, 7, 7, 6, 6, 5, 4, 4, 4, 5, 6, 6, 7, 7, 7, 6, 7, 7, 7, 6, 6, 5, 4, 4, 3, 3, 3, 4, 4, 3, 2, 2, 2, 1, 0, 0, 1, 1, 1, 0, 0, 1, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 2, 1, 0, 0, 1, 1, 1, 0, 0, 1
Offset: 0

Views

Author

Kevin Ryde and Rémy Sigrist, Feb 05 2021

Keywords

Comments

We define the family {C_n, n >= 0}, as follows:
- C_0 corresponds to the points (0, 0), (0, 1), (1, 1), (2, 1) and (2, 0), in that order:
+---+---+
| |
+ +
O
- for any n >= 0, C_{n+1} is obtained by arranging 4 copies of C_n as follows:
+ . . . + . . . +
. B . B .
+ . . . + . . .
. B . .A C.A C.
. . --> + . . . + . . . +
.A C. .C . A.
+ . . . + . B.B .
O .A . C.
+ . . . + . . . +
O
- the space filling curve C is the limit of C_{2*n} as n tends to infinity.

Examples

			Points n and their locations X=A341120(n), Y=a(n) begin as follows.  n=7 and n=9 are both at X=3,Y=2, and n=11,n=31 both at X=3,Y=4.
      |       |
    4 | 16---17   12--11,31
      |  |         |    |
    3 | 15---14---13   10
      |                 |
    2 |            8---7,9
      |                 |
    1 |  1----2----3    6
      |  |         |    |
  Y=0 |  0         4----5
      +--------------------
       X=0    1    2    3
		

Crossrefs

Programs

  • PARI
    See Links section.

Formula

a(2*n) = A341019(n).
a(4*n) = 2*A341120(n).
a(16*n) = 4*a(n).
a(n) = A059253(n) + A283316(n+1).
A059252(n) = (a(4*n+2)-1)/2.

A385414 Number of distinct states of Conway's Game of Life, starting from an n-th level Hilbert curve on a toroidal 2^(n+1)-1 by 2^(n+1)-1 grid.

Original entry on oeis.org

2, 2, 3, 24, 70, 584, 1325, 2082, 5304, 6327, 10679, 11822
Offset: 0

Views

Author

Luke Bennet, Jun 27 2025

Keywords

Comments

The curve is taken with segments of length 2 so that it follows a path through coordinates (2*A059252(t), 2*A059253(t)) for 0 <= t < 2^n.
The size of the toroidal grid is the extent of these coordinates so that the cells on one edge are immediately adjacent to the cells on the opposite side.
The grid has a fixed position and orientation and states differing at any cell are distinct.

Examples

			For n=0, the curve is a single cell on a 1 X 1 toroidal grid and has a(0) = 2 states: initially live, then dead and remaining so.
For n=2 the initial state and two subsequent states are
  o o o . o o o | . . . . . . . | . . . . . . . |
  o . o . o . o | . . . . . . . | . . . . . . . |
  o . o o o . o | . . o . o . . | . . . . . . . |
  o . . . . . o | . . . . . . . | . . . . . . . |
  o o o . o o o | . . o . o . . | . . . . . . . |
  . . o . o . . | . . . . . . . | . . . . . . . |
  o o o . o o o | . . . . . . . | . . . . . . . |
  (generation 1)  (generation 2)  (generation 3)
Every generation after 3 is identical to generation 3, so this sequence has 3 distinct states. Thus, a(2) = 3.
		

Crossrefs

Previous Showing 11-19 of 19 results.