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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A060583 A ternary code related to the Tower of Hanoi.

Original entry on oeis.org

0, 2, 1, 7, 6, 8, 5, 4, 3, 23, 22, 21, 18, 20, 19, 25, 24, 26, 16, 15, 17, 14, 13, 12, 9, 11, 10, 70, 69, 71, 68, 67, 66, 63, 65, 64, 54, 56, 55, 61, 60, 62, 59, 58, 57, 77, 76, 75, 72, 74, 73, 79, 78, 80, 50, 49, 48, 45, 47, 46, 52, 51, 53, 43, 42, 44, 41, 40, 39, 36, 38, 37
Offset: 0

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Author

Henry Bottomley, Apr 04 2001

Keywords

Comments

Write n in base 3, then (working from left to right) if the k-th digit of n is equal to the corresponding digit to the left of the k-th digit of a(n) then this is the k-th digit of a(n), otherwise the k-th digit of a(n) is the element of {0,1,2} which has not just been compared, then read result as a base 3 number.

Examples

			a(46) = 76 since 43 = 1201_3; this gives a first digit of 2(=3-1-0), a second digit of 2(=2=2), a third digit of 1(=3-2-0) and a fourth digit of 1(=1=1); 2211_3 = 76.
		

Crossrefs

Cf. A060586, A060587 (inverse).

Formula

a(n) = 3*a(floor(n/3)) + ((-a(floor(n/3))-n) mod 3) = 3*a(floor(n/3)) + A060582(n) with a(0)=0.

A060588 If the final two digits of n written in base 3 are the same then this digit, otherwise mod 3-sum of these two digits.

Original entry on oeis.org

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

Views

Author

Henry Bottomley, Apr 04 2001

Keywords

Comments

From William Walkington, Sep 14 2016: (Start)
With offset 1, the y-coordinates of position vectors from the origin (point 1) to the points numbered 1 to N^2 of the magic tori that display the Agrippa odd-order-N magic squares can be expressed as follows: a(n) = (-(n-1)-floor((n-1)/N)) mod N.
This generates the y-coordinates of the magic tori that display the Agrippa order-3 "Saturn," order-5 "Mars," order-7 "Venus," order-9 "Luna," and higher-odd-order-N magic squares.
Therefore, if the odd-order-N of the torus is 3, then the resulting sequence 0,2,1,2,1,0,1,0,2 represents the y-coordinates of position vectors from the origin (point number 1) to the point numbered 1 to 9 of the magic torus that displays the Agrippa order-3 "Saturn" magic square. (End)

Examples

			a(22)=1 since 22 is written in base 3 as 211 and the final two digits are 1; a(23)=0 since 23 is written in base 3 as 212 and the final two digits are 1 and 2 and 3-(1+2)=0.
		

References

  • H.C. Agrippa, "De occulta philosophia Libri tres," (1533) translated by "J.F." (John French?) and printed by Moule, London, in 1651, Book II, chapter XXII entitled "Of the tables of the Planets, their vertues,forms, and what Divine names, Intelligencies, and Spirits are set over them."

Crossrefs

Programs

  • Mathematica
    b3d[n_]:=Module[{d3=Take[IntegerDigits[n,3],-2]},If[MatchQ[d3,{x_, x_}], d3[[1]],3-Total[d3]]]; Join[{0,2,1},Array[b3d,110,3]] (* Harvey P. Dale, Feb 29 2016 *)
    Table[If[MatchQ @@ #, First@ #, Mod[3 - Total@ #, 3]] &@ Take[PadLeft[#, 2], -2] &@ IntegerDigits[n, 3], {n, 0, 120}] (* or *)
    Table[Mod[-n - Floor[n/3], 3], {n, 0, 120}] (* Michael De Vlieger, Sep 14 2016 *)

Formula

a(n) = a(n-9) = (-[n/3]-n) mod 3 = A060587(n) mod 3.
a(n) = (-n - floor(n/3)) mod 3. - William Walkington, Sep 14 2016
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