OFFSET
1,2
COMMENTS
Numbers n such that there exists x in N : (x+1)^3 - x^3 = 7*n^2. - Richard Choulet, Oct 16 2008
REFERENCES
E.-A. Majol, Note #2228, L'Intermédiaire des Mathématiciens, 9 (1902), pp. 183-185. - N. J. A. Sloane, Mar 03 2022
LINKS
Colin Barker, Table of n, a(n) for n = 1..450
Index entries for linear recurrences with constant coefficients, signature (110,-1).
FORMULA
a(n+2) = 110*a(n+1)-a(n). - Richard Choulet, Oct 16 2008
G.f.: -x*(x-1) / (x^2-110*x+1). - Colin Barker, Oct 17 2014
EXAMPLE
a(1) = 1 because 2^3-1^3 = 7*1. - Richard Choulet, Oct 16 2008
MATHEMATICA
LinearRecurrence[{110, -1}, {1, 109}, 20] (* Harvey P. Dale, Oct 05 2016 *)
PROG
(PARI) Vec(-x*(x-1)/(x^2-110*x+1) + O(x^20)) \\ Colin Barker, Jul 14 2016
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Richard Choulet, Sep 25 2008
EXTENSIONS
More terms from Colin Barker, Oct 17 2014
STATUS
approved