|
| |
|
|
A290600
|
|
Irregular triangle T(n, k) read by rows: positive numbers non-coprime to A002808(n) and smaller than A002808(n), sorted increasingly.
|
|
3
|
|
|
|
2, 2, 3, 4, 2, 4, 6, 3, 6, 2, 4, 5, 6, 8, 2, 3, 4, 6, 8, 9, 10, 2, 4, 6, 7, 8, 10, 12, 3, 5, 6, 9, 10, 12, 2, 4, 6, 8, 10, 12, 14, 2, 3, 4, 6, 8, 9, 10, 12, 14, 15, 16, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 3, 6, 7, 9, 12, 14, 15, 18
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
The length of row n is A290599(n).
Row n gives the complement of row A038566(A002808(n), k) with respect to [1, 2, ..., A002808(n) - 1].
|
|
|
LINKS
|
Table of n, a(n) for n=1..71.
|
|
|
FORMULA
|
T(n, k) = k-th entry in the list of increasingly sorted numbers of the set {m = 1..A002808(n)-1: gcd(n, m) not equal to 1}.
|
|
|
EXAMPLE
|
The irregular triangle T(n, k) begins (N(n) = A002808(n)):
n N(n) \ k 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ...
1 4 2
2 6 2 3 4
3 8 2 4 6
4 9 3 6
5 10 2 4 5 6 8
6 12 2 3 4 6 8 9 10
7 14 2 4 6 7 8 10 12
8 15 3 5 6 9 10 12
9 16 2 4 6 8 10 12 14
10 18 2 3 4 6 8 9 10 12 14 15 16
11 20 2 4 5 6 8 10 12 14 15 16 18
12 21 3 6 7 9 12 14 15 18
13 22 2 4 6 8 10 11 12 14 16 18 20
14 24 2 3 4 6 8 9 10 12 14 15 16 18 20 21 22
15 25 5 10 15 20
...
|
|
|
MATHEMATICA
|
Table[With[{c = FixedPoint[n + PrimePi@ #] + 1 &, n + PrimePi@ n + 1]}, Select[Range[c - 1], ! CoprimeQ[#, c] &]], {n, 12}] // Flatten (* Michael De Vlieger, Sep 03 2017 *)
|
|
|
CROSSREFS
|
Cf. A002808, A038566, A290599, A290601, A290602.
Sequence in context: A238958 A238971 A194331 * A143595 A211702 A208521
Adjacent sequences: A290597 A290598 A290599 * A290601 A290602 A290603
|
|
|
KEYWORD
|
nonn,tabf
|
|
|
AUTHOR
|
Wolfdieter Lang, Aug 30 2017
|
|
|
STATUS
|
approved
|
| |
|
|
