OFFSET
1,1
COMMENTS
a(n) = 6 if and only if n is an odd prime.
a(n) = 2 if and only if n is a power of 2. - Omar E. Pol, Dec 13 2021
LINKS
FORMULA
a(n) = 2*A204217(n).
EXAMPLE
Illustration of initial terms:
Diagram
n a(n) _ _
1 2 _|1 1|_
2 2 _|1 _ _ 1|_
3 6 _|1 |2 2| 1|_
4 2 _|1 _| |_ 1|_
5 6 _|1 |2 _ _ 2| 1|_
6 8 _|1 _| |3 3| |_ 1|_
7 6 _|1 |2 | | 2| 1|_
8 2 _|1 _| _| |_ |_ 1|_
9 12 _|1 |2 |3 _ _ 3| 2| 1|_
10 10 _|1 _| | |4 4| | |_ 1|_
11 6 _|1 |2 _| | | |_ 2| 1|_
12 8 _|1 _| |3 | | 3| |_ 1|_
13 6 _|1 |2 | _| |_ | 2| 1|_
14 10 _|1 _| _| |4 _ _ 4| |_ |_ 1|_
15 22 _|1 |2 |3 | |5 5| | 3| 2| 1|_
16 2 |1 | | | | | | | | 1|
...
a(n) is the total length of all vertical line segments that are below and that share one vertex with the horizontal line segments that are in the n-th level of the diagram.
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Nov 28 2020
STATUS
approved