|
| |
|
|
A261348
|
|
a(1)=0; a(2)=0; for n>2: a(n) = A237591(n,2) = A237593(n,2).
|
|
2
|
|
|
|
0, 0, 1, 1, 2, 1, 2, 2, 2, 2, 3, 2, 3, 3, 3, 3, 4, 3, 4, 4, 4, 4, 5, 4, 5, 5, 5, 5, 6, 5, 6, 6, 6, 6, 7, 6, 7, 7, 7, 7, 8, 7, 8, 8, 8, 8, 9, 8, 9, 9, 9, 9, 10, 9, 10, 10, 10, 10, 11, 10, 11, 11, 11, 11, 12, 11, 12, 12, 12, 12, 13, 12, 13, 13, 13, 13, 14, 13, 14, 14, 14, 14, 15, 14, 15, 15, 15, 15, 16, 15, 16, 16, 16, 16, 17, 16
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,5
|
|
|
COMMENTS
|
n is an odd prime if and only if a(n) = 1 + a(n-1) and A237591(n,k) = A237591(n-1,k) for the values of k distinct of 2.
For k > 1 there are five numbers k in the sequence.
|
|
|
LINKS
|
|
|
|
EXAMPLE
|
Apart from the initial two zeros the sequence can be written as an array T(j,k) with 6 columns, where row j is [j, j, j+1, j, j+1, j+1], as shown below:
1, 1, 2, 1, 2, 2;
2, 2, 3, 2, 3, 3;
3, 3, 4, 3, 4, 4;
4, 4, 5, 4, 5, 5;
5, 5, 6, 5, 6, 6;
6, 6, 7, 6, 7, 7;
7, 7, 8, 7, 8, 8;
8, 8, 9, 8, 9, 9;
9, 9, 10, 9, 10, 10;
10, 10, 11, 10, 11, 11;
11, 11, 12, 11, 12, 12;
12, 12, 13, 12, 13, 13;
13, 13, 14, 13, 14, 14;
14, 14, 15, 14, 15, 15;
15, 15, 16, 15, 16, 16;
...
Illustration of initial terms:
Row _
1 _| |0
2 _| _|0
3 _| |1|
4 _| _|1|
5 _| |2 _|
6 _| _|1| |
7 _| |2 | |
8 _| _|2 _| |
9 _| |2 | _|
10 _| _|2 | | |
11 _| |3 _| | |
12 _| _|2 | | |
13 _| |3 | _| |
14 _| _|3 _| | _|
15 _| |3 | | | |
16 _| _|3 | | | |
17 _| |4 _| _| | |
18 _| _|3 | | | |
19 _| |4 | | _| |
20 _| _|4 _| | | _|
21 _| |4 | _| | | |
22 _| _|4 | | | | |
23 _| |5 _| | | | |
24 _| _|4 | | _| | |
25 _| |5 | _| | | |
26 | |5 | | | | |
...
The figure represents the triangle A237591 in which the numbers of horizontal cells in the second geometric region gives this sequence, for n > 2.
Note that this is also the second geometric region in the front view of the stepped pyramid described in A245092. For more information see also A237593.
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn,tabf,easy
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
