OFFSET
0,3
COMMENTS
The irrational parts are given in A251631.
The points of the lattice of the Archimedean tiling (4,8,8) lie on certain circles around any point. The length of the regular octagon (8-gon) side is taken as 1 (in some length unit).
The squares of the radii R2(n) of these circles are integers in the real quadratic number field Q(sqrt(2)), hence R2(n) = a(n) + A251631(n)*sqrt(2). The R2 sequence is sorted in increasing order.
LINKS
Wolfdieter Lang, On lattice point circles for the Archimedean tiling (4,8,8).
Wikipedia, Archimedean tilings
EXAMPLE
The first pairs [a(n), A251631(n)] for the squared radii are: [0,0], [1,0], [2,0], [2,1], [3,2], [4,2], [5,2] [6,3], [6,4], [7,4], [9,4], [9,6], [11,6], [10,7], [12,6], [12,8], [13,8], ...
The corresponding radii are (Maple 10 digits if not integer) 0, 1, 1.414213562, 1.847759065, 2.414213562, 2.613125930, 2.797932652, 3.200412581, 3.414213562, 3.557647291, 3.828427124, 4.181540551, 4.414213562, 4.460884994, 4.526066876, 4.828427124, 4.930893276, ...
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Jan 02 2015
STATUS
approved