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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A163361 Hilbert curve in N x N grid, one-based, starting rightwards from the top-left corner.

Original entry on oeis.org

1, 2, 4, 15, 3, 5, 16, 14, 8, 6, 17, 13, 9, 7, 59, 20, 18, 12, 10, 58, 60, 21, 19, 31, 11, 55, 57, 61, 22, 24, 30, 32, 54, 56, 62, 64, 235, 23, 25, 29, 33, 53, 51, 63, 65, 236, 234, 26, 28, 36, 34, 52, 50, 68, 66, 237, 233, 231, 27, 37, 35, 47, 49, 69, 67, 79, 240, 238, 232
Offset: 1

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Author

Antti Karttunen, Jul 29 2009

Keywords

Crossrefs

Inverse: A163362. Transpose: A163363.

Formula

a(n) = A163357(n-1)+1

A165467 Positions of zeros in A165466. Fixed points of A166043/A166044.

Original entry on oeis.org

0, 8, 9, 105, 1126, 6643718, 6643719, 6643727, 6643728, 6643729, 6643735, 6643736, 6643743, 6643744, 6643745, 6643752, 7746856, 7746857, 7746886, 7746887, 7746888, 7746889, 7747606, 7747718, 7747719, 7747720, 7747737
Offset: 0

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Author

Antti Karttunen, Oct 06 2009

Keywords

Comments

Here is a little parable for illustrating the magnitudes of the numbers involved. Consider two immortal sage kings traveling on the infinite chessboard, visiting every square at a leisurely pace of one square per day. Both start their journey at the beginning of the year from the upper left-hand corner square at Day 0 (being sages, they can comfortably stay in the same square). One decides to follow the Hilbert curve (as in A163357) on his never-ending journey, while the other follows the Peano curve (as in A163336; both walks are illustrated in entry A166043). This sequence gives the days when they will meet, when they both arrive at the same square on the same day.
From the corner, one king walks first towards the east, while the other walks towards the south, so their paths diverge at the beginning. However, about a week later (Day 8), they meet again on square (2,2), two squares south and two squares east of the starting corner. The next day they are both traveling towards the south, so they meet also on Day 9, at square (3,2). After that, they meet briefly three months later (Day 105), and also about three years later (Day 1126), after which they loathe each other so much that they both walk in solitude for the next 18189 (eighteen thousand one hundred and eighty nine) years before they meet again, total of eleven times in just about one month's time (days 6643718-6643752). - Antti Karttunen, Oct 13 2009 [Edited to Hilbert vs Peano by Kevin Ryde, Aug 29 2020]

Crossrefs

Subset of A165480. Cf. also A165465, A163901.

A163897 a(n) = A163531(n)-A163547(n).

Original entry on oeis.org

0, 0, 2, 4, -2, -8, -6, 0, 0, 0, 2, 16, 16, 12, 6, 0, 0, 8, 10, 24, 28, 16, 0, 0, 0, 0, 10, 28, 24, 16, 32, 40, 48, 48, 24, 20, -2, -24, -40, -36, -40, -44, -64, -60, -56, -48, -42, -56, -42, -36, -20, -16, -8, 0, 16, 8, 14, 36, 34, 24, 28, 28, 18, 24, 16, 8, -8, 0, -10
Offset: 0

Views

Author

Antti Karttunen, Sep 19 2009

Keywords

Comments

This sequence gives the difference of squares of distance from the origin to the n-th term, in the Peano curve (A163334) and the Hilbert curve (A163357) on an N x N grid. Because the Hilbert curve is based on powers of 4 and the Peano curve on powers of 9, the graph of this sequence contains dramatic swings. [Edited to Peano vs Hilbert by Kevin Ryde, Aug 28 2020]

Crossrefs

Cf. A165480 (positions of 0's).

A163907 Permutation A163905 shown in N x N grid.

Original entry on oeis.org

0, 1, 2, 9, 3, 14, 10, 11, 12, 15, 16, 8, 4, 13, 47, 18, 19, 6, 7, 45, 44, 20, 17, 27, 5, 39, 46, 40, 21, 22, 25, 26, 37, 38, 41, 42, 149, 23, 30, 24, 58, 36, 33, 43, 234, 150, 151, 29, 28, 56, 57, 34, 35, 232, 235, 152, 148, 157, 31, 54, 59, 49, 32, 236, 233, 227, 154
Offset: 0

Views

Author

Antti Karttunen, Sep 19 2009

Keywords

Examples

			The top left 8x8 corner of this array:
+0 +1 +9 10 16 18 20 21
+2 +3 11 +8 19 17 22 23
14 12 +4 +6 27 25 30 29
15 13 +7 +5 26 24 28 31
47 45 39 37 58 56 54 53
44 46 38 36 57 59 52 55
40 41 33 34 49 51 60 61
42 43 35 32 48 50 62 63
		

Crossrefs

Inverse: A163908. a(n) = A163905(A054238(n)) = A163355(A163357(n)). See also A163357, A163917.

A163917 Permutation A163915 shown in N x N grid.

Original entry on oeis.org

0, 1, 3, 7, 2, 9, 5, 6, 8, 10, 16, 4, 14, 11, 48, 17, 18, 13, 12, 51, 50, 20, 19, 28, 15, 52, 49, 60, 21, 23, 29, 31, 53, 55, 61, 63, 127, 22, 27, 30, 47, 54, 57, 62, 149, 125, 126, 25, 24, 46, 45, 59, 56, 148, 150, 118, 124, 113, 26, 39, 44, 35, 58, 152, 151, 146, 117
Offset: 0

Views

Author

Antti Karttunen, Sep 19 2009

Keywords

Examples

			The top left 8x8 corner of this array:
+0 +1 +7 +5 16 17 20 21
+3 +2 +6 +4 18 19 23 22
+9 +8 14 13 28 29 27 25
10 11 12 15 31 30 24 26
48 51 52 53 47 46 39 37
50 49 55 54 45 44 36 38
60 61 57 59 35 34 40 41
63 62 56 58 32 33 43 42
		

Crossrefs

Inverse: A163918. a(n) = A163915(A054238(n)) = A163355(A163907(n)) = A163905(A163357(n)). See also A163357, A163907.

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))).

A262174 Sierpiński arrowhead curve as a triangular array starting leftward from the top, read by rows.

Original entry on oeis.org

1, 2, 0, 0, 3, 4, 9, 8, 0, 5, 10, 0, 7, 6, 0, 0, 11, 0, 0, 23, 24, 13, 12, 0, 0, 22, 0, 25, 14, 0, 17, 18, 0, 21, 26, 0, 0, 15, 16, 0, 19, 20, 0, 27, 28, 69, 68, 0, 0, 0, 0, 0, 0, 0, 29, 70, 0, 67, 0, 0, 0, 0, 0, 31, 30, 0, 0, 71, 66, 0, 0, 0, 0, 0, 32, 0, 35, 36
Offset: 1

Views

Author

Max Barrentine, Sep 13 2015

Keywords

Comments

The triangle up to the (1 + 2^n)th row is the n-th iteration of the curve, rotated such that the curve begins at the top and continues down to the left.
As this is not a space-filling curve, not all points on the triangular lattice are reached by the curve; these points are given the value 0.

Examples

			The first 5 rows of this triangle show how this curve begins (connect the terms in numerical order):
            1;
          2,  0;
        0,  3,  4;
      9,  8,  0,  5;
   10,  0,  7,  6,  0;
   ...
		

Crossrefs

See also A163357, A163334, and A054238 for other fractal curves.

A265318 Fibonacci word fractal in an n X n grid, starting downwards from the top-left corner, listed antidiagonally.

Original entry on oeis.org

1, 0, 2, 5, 3, 0, 6, 4, 0, 0, 7, 0, 0, 0, 0, 0, 8, 10, 0, 0, 20, 0, 0, 9, 11, 0, 19, 21, 0, 0, 0, 0, 12, 18, 0, 22, 0, 0, 0, 0, 13, 0, 17, 23, 0, 0, 0, 0, 0, 0, 14, 16, 0, 24, 26, 0, 0, 0, 0, 0, 0, 15, 0, 0, 25, 27, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 28, 83
Offset: 1

Views

Author

Max Barrentine, Dec 06 2015

Keywords

Comments

The n-th iteration of this curve ends at the n-th Fibonacci number.
As this is not a space-filling curve, not all points on the grid are reached by the curve; these points are given the value 0.

Examples

			The top left corner of the array shows how this curve begins (connect the terms in numerical order):
   1   0   5   6   7
   2   3   4   0   8
   0   0   0  10   9
   0   0   0  11   0
   0   0   0  12  13
  20  19  18   0  14
  21   0  17  16  15
  22  23   0   0   0
   0  24   0   0   0
  26  25   0   0   0
  27   0  31  32  33
  28  29  30   0  34
		

Crossrefs

See also A163357, A163334, and A054238 for other fractal curves.
Previous Showing 31-38 of 38 results.