OFFSET
0,6
COMMENTS
The toothpick structure has the property that the number of exposed endpoints in the row 2k equals the number of divisors of k, if 1<2k<n, k>=1. See example and Link section.
LINKS
Omar E. Pol, Illustration of initial terms of the divisor function (A000005), see the third picture.
N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS
EXAMPLE
Illustration of initial terms:
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n a(n) Diagram A000005
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0 0
1 0
2 0 1
3 1 |
4 1 2
5 2 |
6 2 2
7 3 |
8 3 3
9 5 | |
10 6 | 2
11 8 | |
12 8 4
13 10 | |
14 11 | 2
15 13 | |
16 13 4
17 15 | |
18 16 | 3
19 19 | | |
20 20 | 4
21 23 | | |
22 25 | | 2
23 28 | | |
24 28 6
25 31 | | |
26 33 | | 2
27 36 | | |
28 37 | 4
29 40 | | |
30 41 | 4
31 44 | | |
32 45 | 5
33 49 | | | |
...
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Oct 04 2013
STATUS
approved