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Triangle read by rows: frequency with which the number of values taken by cos(2*Pi/k) mod j occurs for each j >= 1, taken over k = 1..j-1.
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%I #12 Jan 18 2024 07:49:04

%S 0,0,1,0,1,1,0,2,1,0,0,1,3,0,0,0,3,0,0,1,1,0,2,3,0,1,0,0,0,4,0,0,2,0,

%T 0,1,0,3,1,1,2,0,1,0,0,0,3,2,0,1,2,0,0,1,0,0,2,5,1,1,0,1,0,0,0,0,0,6,

%U 0,0,3,0,0,0,0,0,0,2,0,3,6,0,2,0,1,0,0,0,0,0,0,0,5,2,0,2,1,0,0,1,2,0,0,0,0

%N Triangle read by rows: frequency with which the number of values taken by cos(2*Pi/k) mod j occurs for each j >= 1, taken over k = 1..j-1.

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

%H Christopher Hunt Gribble, <a href="/A164846/b164846.txt">Flattened triangle, for j = 1..100 and k = 1..j-1</a>.

%e The triangle of numbers is:

%e ..j....Frequency of numbers of solutions over k

%e .......0..1..2..3..4..5..6..7..8..9..10

%e ..1....0

%e ..2....0..1

%e ..3....0..1..1

%e ..4....0..2..1..0

%e ..5....0..1..3..0..0

%e ..6....0..3..0..0..1..1

%e ..7....0..2..3..0..1..0..0

%e ..8....0..4..0..0..2..0..0..1

%e ..9....0..3..1..1..2..0..1..0..0

%e .10....0..3..2..0..1..2..0..0..1..0

%e .11....0..2..5..1..1..0..1..0..0..0..0

%Y Cf. A164822, A164823, A164831, A165252.

%K nonn,tabl

%O 1,8

%A _Christopher Hunt Gribble_, Aug 28 2009

%E Minor edits from _N. J. A. Sloane_, Sep 01 2009

%E Sequence corrected by _Christopher Hunt Gribble_, Sep 10 2009

%E Minor edits by _Christopher Hunt Gribble_, Oct 01 2009