OFFSET
1,1
COMMENTS
Also positive integers x in the solutions to 12*x^2-5*y^2+32*x+3*y+36 = 0, the corresponding values of y being A252770.
LINKS
Colin Barker, Table of n, a(n) for n = 1..557
Index entries for linear recurrences with constant coefficients, signature (63,-63,1).
FORMULA
a(n) = 63*a(n-1)-63*a(n-2)+a(n-3).
G.f.: 2*x*(7*x-47) / ((x-1)*(x^2-62*x+1)).
a(n) = 2*(-2/3+1/240*(31+8*sqrt(15))^(-n)*(80-27*sqrt(15)+(31+8*sqrt(15))^(2*n)*(80+27*sqrt(15)))). - Colin Barker, Mar 03 2016
EXAMPLE
94 is in the sequence because P(94)+P(95)+P(96)+P(97) = 13207+13490+13776+14065 = 54538 = H(148).
MATHEMATICA
LinearRecurrence[{63, -63, 1}, {94, 5908, 366282}, 30] (* Harvey P. Dale, Mar 04 2015 *)
PROG
(PARI) Vec(2*x*(7*x-47)/((x-1)*(x^2-62*x+1)) + O(x^100))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Dec 21 2014
STATUS
approved