|
|
A326777
|
|
Lexicographically earliest sequence of distinct positive integers such that for any n > 0, the area of the triangle ((n, a(n)), (n+1, a(n+1)), (n+2, a(n+2))) is unique.
|
|
1
|
|
|
1, 2, 3, 5, 4, 7, 8, 14, 6, 9, 18, 10, 11, 19, 12, 13, 24, 15, 22, 16, 28, 17, 25, 21, 38, 20, 26, 54, 23, 29, 60, 27, 30, 59, 31, 32, 61, 34, 37, 67, 35, 36, 68, 33, 39, 77, 40, 41, 76, 42, 47, 92, 43, 44, 87, 45, 46, 91, 48, 50, 98, 49, 51, 100, 53, 55, 105
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
For any n > 0, the area of the triangle ((n, a(n)), (n+1, a(n+1)), (n+2, a(n+2))) equals abs(2*a(n+1) - a(n) - a(n+2)).
This sequence has similarities with A081145; here the absolute value of the second difference is unique, there the absolute value of the first difference.
|
|
LINKS
|
|
|
EXAMPLE
|
The first terms, alongside the area of the n-th triangle, are:
n a(n) Area
-- ---- ----
1 1 0
2 2 1
3 3 3
4 5 4
5 4 2
6 7 5
7 8 14
8 14 11
9 6 6
10 9 17
11 18 9
12 10 7
13 11 15
|
|
PROG
|
(PARI) See Links section.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|