OFFSET
1,2
COMMENTS
Also values x of Pythagorean triples (x, x+167, y).
Corresponding values y of solutions (x, y) are in A159777.
lim_{n -> infinity} a(n)/a(n-3) = 3+2*sqrt(2).
lim_{n -> infinity} a(n)/a(n-1) = (171+26*sqrt(2))/167 for n mod 3 = {1, 2}.
lim_{n -> infinity} a(n)/a(n-1) = (56211+34510*sqrt(2))/167^2 for n mod 3 = 0.
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,6,-6,0,-1,1).
FORMULA
a(n) = 6*a(n-3)-a(n-6)+334 for n > 6; a(1)=0, a(2)=28, a(3)=385, a(4)=501, a(5)=645, a(6)=2668.
G.f.: x*(28+357*x+116*x^2-24*x^3-119*x^4-24*x^5)/((1-x)*(1-6*x^3+x^6)).
a(3*k+1) = 167*A001652(k) for k >= 0.
MATHEMATICA
LinearRecurrence[{1, 0, 6, -6, 0, -1, 1}, {0, 28, 385, 501, 645, 2668, 3340}, 80] (* Vladimir Joseph Stephan Orlovsky, Feb 07 2012 *)
PROG
(PARI) {forstep(n=0, 100000000, [1, 3], if(issquare(2*n^2+334*n+27889), print1(n, ", ")))}
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mohamed Bouhamida, Jun 17 2007
EXTENSIONS
Edited and two terms added by Klaus Brockhaus, Apr 30 2009
STATUS
approved