OFFSET
1,1
LINKS
Colin Barker, Table of n, a(n) for n = 1..831
Index entries for linear recurrences with constant coefficients, signature (1,254,-254,-1,1).
FORMULA
a(n) = a(n-1)+254*a(n-2)-254*a(n-3)-a(n-4)+a(n-5) for n>5.
G.f.: 7*x*(4*x^4+16*x^3-381*x^2-16*x-1) / ((x-1)*(x^2-16*x+1)*(x^2+16*x+1)).
EXAMPLE
7 is in the sequence because (7+21)^3 - 7^3 = 147^2.
MATHEMATICA
LinearRecurrence[{1, 254, -254, -1, 1}, {7, 119, 4564, 32900, 1161895}, 20] (* Harvey P. Dale, Jan 11 2017 *)
PROG
(PARI) Vec(7*x*(4*x^4+16*x^3-381*x^2-16*x-1)/((x-1)*(x^2-16*x+1)*(x^2+16*x+1)) + O(x^30))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Oct 30 2015
STATUS
approved