OFFSET
1,2
COMMENTS
Also positive integers x in the solutions to 5*x^2 - 8*y^2 - 5*x + 8*y = 0, the corresponding values of y being A253411.
LINKS
Colin Barker, Table of n, a(n) for n = 1..633
Index entries for linear recurrences with constant coefficients, signature (1,1442,-1442,-1,1).
FORMULA
a(n) = a(n-1) + 1442*a(n-2) - 1442*a(n-3) - a(n-4) + a(n-5).
G.f.: x*(95*x^3 + 721*x^2 - 95*x - 1) / ((x-1)*(x^2 - 38*x + 1)*(x^2 + 38*x + 1)).
EXAMPLE
96 is in the sequence because the 96th centered pentagonal number is 22801, which is also the 76th centered octagonal number.
MATHEMATICA
LinearRecurrence[{1, 1442, -1442, -1, 1}, {1, 96, 817, 137712, 1177393}, 20] (* Harvey P. Dale, Jul 12 2021 *)
PROG
(PARI) Vec(x*(95*x^3+721*x^2-95*x-1)/((x-1)*(x^2-38*x+1)*(x^2+38*x+1)) + O(x^100))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Dec 31 2014
STATUS
approved