A165609 Irregular triangle read by rows: Nonexistent values of cos(2*Pi/k) mod j, for j >= 2 and 1 <= k <= j-1.

2, 3, 2, 5, 3, 8, 3, 8, 9, 2, 5, 10, 3, 4, 15, 16, 4, 10, 13, 19, 4, 19, 22, 27, 2, 5, 10, 11, 20, 21, 26, 29, 3, 6, 9, 15, 20, 24, 25, 32, 33, 5, 6, 10, 11, 33, 37, 3, 8, 9, 13, 20, 23, 30, 34, 35, 40, 4, 10, 18, 19, 28, 29, 37, 43

Offset

1,1

Comments

See A164823 for explanatory comment and the definition of "cos(x) mod j".

Links

Christopher Hunt Gribble, Flattened irregular triangle, for 2 < j < 1000.

Example

The irregular triangle of numbers without empty rows is:
..j....Nonexistent values of cos(2*Pi/k) mod j
..4....2
..5....3
..7....2..5
.11....3..8
.13....3..8..9
.17....2..5.10
.19....3..4.15.16
.23....4.10.13.19
.29....4.19.22.27
.31....2..5.10.11.20.21.26.29
.37....3..6..9.15.20.24.25.32.33
.41....5..6.10.11.33.37
.43....3..8..9.13.20.23.30.34.35.40
.47....4.10.18.19.28.29.37.43

Crossrefs

Cf: A164823, A165252.

Sequence in context: A075105 A265675 A094020 * A358462 A141465 A263216

Adjacent sequences: A165606 A165607 A165608 * A165610 A165611 A165612

Keyword

nonn,tabf

Author

Christopher Hunt Gribble, Sep 22 2009

Extensions

Minor edits from N. J. A. Sloane, Sep 25 2009

Minor edit by Christopher Hunt Gribble, Oct 01 2009

Status

approved