OFFSET
1,1
COMMENTS
Also nonnegative integers y in the solutions to 3*x^2-y^2+2*x-2*y = 0, the corresponding values of x being A122770.
LINKS
Colin Barker, Table of n, a(n) for n = 1..874
Index entries for linear recurrences with constant coefficients, signature (15,-15,1).
FORMULA
a(n) = 15*a(n-1)-15*a(n-2)+a(n-3).
G.f.: -2*x*(x+5) / ((x-1)*(x^2-14*x+1)).
a(n) = (-6-(7-4*sqrt(3))^n*(-3+sqrt(3))+(3+sqrt(3))*(7+4*sqrt(3))^n)/6. - Colin Barker, Mar 05 2016
EXAMPLE
10 is in the sequence because T(10)+T(11) = 55+56 = 121 = 51+70 = P(6)+P(7).
MATHEMATICA
LinearRecurrence[{15, -15, 1}, {10, 152, 2130}, 30] (* Harvey P. Dale, Jun 08 2016 *)
PROG
(PARI) Vec(-2*x*(x+5)/((x-1)*(x^2-14*x+1)) + O(x^100))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Dec 07 2014
STATUS
approved