OFFSET
1,2
LINKS
Colin Barker, Table of n, a(n) for n = 1..465
Index entries for linear recurrences with constant coefficients, signature (143,-143,1).
FORMULA
a(n) = 143*a(n-1)-143*a(n-2)+a(n-3).
G.f.: -x*(x^2-37*x+1) / ((x-1)*(x^2-142*x+1)).
a(n) = (4+(6+sqrt(35))*(71+12*sqrt(35))^(-n)-(-6+sqrt(35))*(71+12*sqrt(35))^n)/16. - Colin Barker, Mar 07 2016
EXAMPLE
106 is in the sequence because it is the 6th centered heptagonal number and the 7th centered pentagonal number.
MATHEMATICA
LinearRecurrence[{143, -143, 1}, {1, 106, 15016}, 20] (* Harvey P. Dale, Feb 25 2016 *)
PROG
(PARI) Vec(-x*(x^2-37*x+1)/((x-1)*(x^2-142*x+1)) + O(x^100))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Jan 06 2015
STATUS
approved