OFFSET
1,2
COMMENTS
(1) Row 1 of R consists of principal convergents to x.
(2) (row limits of R) = x; (column limits of R) = 0.
(3) Every positive integer occurs exactly once in D, so that as a sequence, A143516 is a permutation of the positive integers.
FORMULA
For any positive irrational number x, define an array D by successive rows as follows: D(n,k) = least positive integer q not already in D such that there exists an integer p such that 0 < |x - p/q| < |x - c/d| for every positive rational number c/d that has 0 < d < q. Thus p/q is the "best remaining approximate" of x when all better approximates are unavailable. For each q, define N(n,k)=p and R(n,k)=p/q. Then R is the "array of best remaining approximates of x," D is the corresponding array of denominators and N, of numerators.
EXAMPLE
Northwest corner of D:
1 2 3 5
4 6 7 10
9 11 15 19
12 14 20 27
Northwest corner of R:
2/1 3/2 5/3 8/5
6/4 10/6 11/7 16/10
15/9 18/11 24/15 31/19
19/12 23/14 32/20 44/27
CROSSREFS
KEYWORD
AUTHOR
Clark Kimberling, Aug 22 2008
STATUS
approved