OFFSET
1,2
LINKS
Peter Kagey, Table of n, a(n) for n = 1..1000
Code Golf Stack Exchange, Concentric rings on a snub square tiling.
Index entries for linear recurrences with constant coefficients, signature (2,-1).
FORMULA
a(n) = 12*(n - 1) for n > 4.
From Stefano Spezia, Feb 05 2020: (Start)
G.f.: x*(1 + 7*x + 4*x^2 + 2*x^3 - x^4 - x^5)/(-1 + x)^2.
a(n) = 2*a(n-1) - a(n-2) for n > 6.
(End)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Peter Kagey, Feb 04 2020
STATUS
approved