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 1-5 of 5 results.

A163334 Peano curve in an n X n grid, starting rightwards from the top left corner, listed antidiagonally as A(0,0), A(0,1), A(1,0), A(0,2), A(1,1), A(2,0), ... .

Original entry on oeis.org

0, 1, 5, 2, 4, 6, 15, 3, 7, 47, 16, 14, 8, 46, 48, 17, 13, 9, 45, 49, 53, 18, 12, 10, 44, 50, 52, 54, 19, 23, 11, 43, 39, 51, 55, 59, 20, 22, 24, 42, 40, 38, 56, 58, 60, 141, 21, 25, 29, 41, 37, 69, 57, 61, 425, 142, 140, 26, 28, 30, 36, 70, 68, 62, 424, 426, 143, 139
Offset: 0

Views

Author

Antti Karttunen, Jul 29 2009

Keywords

Examples

			The top left 9 X 9 corner of the array shows how this surjective self-avoiding walk begins (connect the terms in numerical order, 0-1-2-3-...):
   0  1  2 15 16 17 18 19 20
   5  4  3 14 13 12 23 22 21
   6  7  8  9 10 11 24 25 26
  47 46 45 44 43 42 29 28 27
  48 49 50 39 40 41 30 31 32
  53 52 51 38 37 36 35 34 33
  54 55 56 69 70 71 72 73 74
  59 58 57 68 67 66 77 76 75
  60 61 62 63 64 65 78 79 80
		

Crossrefs

Transpose: A163336. Inverse: A163335. One-based version: A163338. Row sums: A163342. Row 0: A163480. Column 0: A163481. Central diagonal: A163343.
See A163357 and A163359 for the Hilbert curve.

Programs

  • Mathematica
    b[{n_, k_}, {m_}] := (A[k, n] = m - 1);
    MapIndexed[b, List @@ PeanoCurve[4][[1]]];
    Table[A[n - k, k], {n, 0, 12}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Mar 07 2021 *)

Formula

a(n) = A163332(A163328(n)).

Extensions

Links to further derived sequences added by Antti Karttunen, Sep 21 2009
Name corrected by Kevin Ryde, Aug 22 2020

A163534 The absolute direction (0=east, 1=south, 2=west, 3=north) of the Peano curve A163334 at point n.

Original entry on oeis.org

0, 0, 1, 2, 2, 1, 0, 0, 0, 0, 0, 3, 2, 2, 3, 0, 0, 0, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 2, 2, 2, 3, 0, 0, 3, 2, 2, 2, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 0, 0, 0, 3, 2, 2, 3, 0, 0, 0, 0, 0, 1, 2, 2, 1, 0, 0, 0, 0, 0, 3, 2, 2, 3, 0, 0, 0, 0, 0, 1, 2, 2, 1, 0, 0, 0, 0, 0, 3
Offset: 1

Views

Author

Antti Karttunen, Aug 01 2009

Keywords

Comments

Taking every ninth term gives the same sequence: (and similarly for all higher powers of 9 as well): a(n) = a(9*n).

Crossrefs

Cf. A163535 (transposed direction), A163536 (turn).

Programs

Formula

a(n) = A010873(A163532(n)+A163533(n)+abs(A163533(n))+3).
a(n) = A004442(A163535(n)).

Extensions

Name corrected by Kevin Ryde, Aug 29 2020

A163532 The change in X-coordinate when moving from the n-1:th to the n-th point in the Peano curve A163334.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 01 2009

Keywords

Crossrefs

A014578(n) = |a(n)|. These are the first differences of A163528. See also: A163533, A163534, A163536.

Formula

a(0)=0, a(n) = A163528(n) - A163528(n-1).

Extensions

Name corrected by Kevin Ryde, Aug 28 2020

A163533 The change in Y-coordinate when moving from the n-1:th to the n-th point in the Peano curve A163334.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 01 2009

Keywords

Crossrefs

These are the first differences of A163529. See also: A163532, A163534, A163536.

Formula

a(0)=0, a(n) = A163529(n) - A163529(n-1).

Extensions

Name corrected by Kevin Ryde, Aug 29 2020

A163537 The relative direction (0=straight ahead, 1=turn right, 2=turn left) of the Peano curve A163336 at point n.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 01 2009

Keywords

Comments

a(9*n) = a(81*n) for all n.

Crossrefs

Cf. A163535 (direction), A163536 (transposed relative).

Programs

Formula

a(n) = A163241((A163535(n+1)-A163535(n)) modulo 4).
a(n) = A014681(A163536(n)).

Extensions

Name corrected by Kevin Ryde, Aug 29 2020
Showing 1-5 of 5 results.