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A366353 a(0) = 0; for n > 0, a(n) is the largest taxicab distance on a square spiral between a(n-1) and any previous occurrence of a(n-1). If a(n-1) has not previously occurred then a(n) = 0. 4
0, 0, 1, 0, 2, 0, 2, 2, 3, 0, 4, 0, 4, 2, 5, 0, 6, 0, 6, 2, 6, 4, 7, 0, 6, 8, 0, 7, 5, 4, 8, 5, 3, 4, 6, 8, 10, 0, 9, 0, 7, 7, 8, 12, 0, 7, 6, 8, 10, 12, 6, 10, 11, 0, 9, 8, 13, 0, 11, 6, 9, 6, 11, 10, 13, 8, 12, 13, 11, 10, 9, 12, 8, 15, 0, 13, 13, 12, 11, 12, 13, 16, 0, 13, 15, 11, 11, 10, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,5
LINKS
Scott R. Shannon, Image of the first 50000 terms on the square spiral. The colors are graduated across the spectrum to show their relative size. Zoom in to see the numbers.
EXAMPLE
The spiral begins:
.
.
10--8---6---4---3---5---8 :
| | :
0 6---0---5---2---4 4 9
| | | | |
9 0 2---0---1 0 5 0
| | | | | | |
0 6 0 0---0 4 7 11
| | | | | |
7 2 2---2---3---0 0 10
| | | |
7 6---4---7---0---6---8 6
| |
8---12--0---7---6---8---10--12
.
a(2) = 1 as the taxicab distance between a(1) = 0, at (1,0) relative to the starting square, and the only previous occurrence of 0, a(0) at (0,0), is 1.
a(8) = 3 as the maximum taxicab distance between a(7) = 2, at (0,-1) relative to the starting square, and any previous occurrence of 2 is 3, to a(4) = 2 at (-1,1) relative to the starting square.
a(32) = 3 as the maximum taxicab distance between a(31) = 5, at (2,3) relative to the starting square, and any previous occurrence of 5 is 3, to a(28) = 5 at (3,1) relative to the starting square, and also to a(14) = 5 at (0,2) relative to the starting square. This is the first term to differ from A366354.
CROSSREFS
Sequence in context: A352128 A334203 A309107 * A366354 A144741 A352965
KEYWORD
nonn
AUTHOR
Scott R. Shannon, Oct 08 2023
STATUS
approved

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Last modified May 16 03:14 EDT 2024. Contains 372549 sequences. (Running on oeis4.)