OFFSET
1,2
COMMENTS
Numbers X such that 140*X^2-84*X-7 is a square.
LINKS
Index entries for linear recurrences with constant coefficients, signature (13, -13, 1).
FORMULA
a(n+2)=12*a(n+1)-a(n)-3 ; a(n+1)=6*a(n)-1.5+0.5*(140*a(n)^2-84*a(n)-7)^0.5
G.f.: -x*(1-5*x+x^2)/(-1+x)/(1-12*x+x^2). - R. J. Mathar, Nov 14 2007
a(1)=1, a(2)=8, a(3)=92, a(n)=13*a(n-1)-13*a(n-2)+a(n-3). - Harvey P. Dale, Mar 24 2013
MATHEMATICA
LinearRecurrence[{13, -13, 1}, {1, 8, 92}, 30] (* Harvey P. Dale, Mar 24 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Richard Choulet, Oct 16 2007
EXTENSIONS
More terms from Paolo P. Lava, Jul 08 2008
STATUS
approved