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A229950
Total number of toothpicks after n-th stage in a toothpick structure in which the toothpicks represent the 1's of triangle A229940.
6
0, 0, 0, 1, 1, 2, 2, 3, 3, 5, 6, 8, 8, 10, 11, 13, 13, 15, 16, 19, 20, 23, 25, 28, 28, 31, 33, 36, 37, 40, 41, 44, 45, 49, 52, 56, 57, 61, 64, 68, 69, 73, 75, 79, 81, 85, 88, 92, 92, 96, 99, 104, 107, 112, 115, 120, 122, 127, 131, 136, 137, 142, 146, 151, 153
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.
EXAMPLE
Illustration of initial terms:
---------------------------------------
n a(n) Diagram A000005
---------------------------------------
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
Partial sums of A229951.
Sequence in context: A062303 A180682 A227426 * A050318 A130841 A002095
KEYWORD
nonn
AUTHOR
Omar E. Pol, Oct 04 2013
STATUS
approved