OFFSET
0,1
COMMENTS
Inspired by Vitruvian Man, but using hexagons instead of squares, starting with a hexagon whose sides are of length 4 (in some units). The radius of the circle is an integer in the real quadratic number field Q(sqrt(3)), namely R(n) = A(n) + B(n)*sqrt(3) with A(0)=2, A(n) = a(n), and B(0) = 1, B(n) = A255163(n). See illustrations in the links.
LINKS
Kival Ngaokrajang, Illustration of initial terms, Vitruvian Man
FORMULA
Conjectures from Colin Barker, Feb 15 2015: (Start)
a(n) = -12*a(n-1) + 12*a(n-2).
G.f.: -2*(12*x+1) / (12*x^2 - 12*x - 1).
(End)
PROG
(PARI){a=2; b=1; print1(a, ", "); for(n=1, 30, c=12*b-6*a; d=4*a-6*b; print1(c, ", "); a=c; b=d)}
CROSSREFS
KEYWORD
sign
AUTHOR
Kival Ngaokrajang, Feb 15 2015
STATUS
approved