OFFSET
0,2
COMMENTS
15*a(n)^2 - 11 is a square for all terms.
x = a(n) and y = a(n+1) satisfy x^2 + y^2 - 8*x*y = -11.
x = a(n) and y = a(n+2) satisfy x^2 + y^2 - 62*x*y = -704.
LINKS
FORMULA
a(0) = 1; a(1) = 6; a(n) = 8*a(n-1) - a(n-2).
G.f.: (1 - 2*x)/(1 - 8*x + x^2). - Stefano Spezia, Feb 26 2021
a(n) = A237262(2*n + 1).
EXAMPLE
a(3) = 8*6 - 1 = 47.
MATHEMATICA
LinearRecurrence[{8, -1}, {1, 6}, 15]
PROG
(PARI) my(p=Mod('x, 'x^2-8*'x+1)); a(n) = subst(lift(p^n), 'x, 6); \\ Kevin Ryde, Mar 01 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
John O. Oladokun, Feb 23 2021
STATUS
approved