OFFSET
1,2
LINKS
Colin Barker, Table of n, a(n) for n = 1..354
Index entries for linear recurrences with constant coefficients, signature (675,-675,1).
FORMULA
a(n) = 675*a(n-1)-675*a(n-2)+a(n-3).
G.f.: -x*(x^2-128*x+1) / ((x-1)*(x^2-674*x+1)).
EXAMPLE
547 is in the sequence because it is the 14th centered hexagonal number and the 13th centered heptagonal number.
MATHEMATICA
LinearRecurrence[{675, -675, 1}, {1, 547, 368551}, 20] (* Harvey P. Dale, Aug 03 2021 *)
PROG
(PARI) Vec(-x*(x^2-128*x+1) / ((x-1)*(x^2-674*x+1)) + O(x^100))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Jan 03 2015
STATUS
approved