OFFSET
0,2
REFERENCES
D. A. Cox, Primes of the form x^2+ny^2, Wiley, New York, 1989.
D. E. Flath, Introduction to Number Theory, Wiley-Interscience, 1989.
LINKS
FORMULA
G.f.: (1-6*x^2)/(1-6*x-42*x^2) . a(n) = Sum_{k, 0<=k<=n}A122950(n,k)*6^k .
a(1)=6, a(2)=72, a(n)=6*a(n-1)+42*a (n-2). - Harvey P. Dale, Mar 25 2015
MATHEMATICA
Join[{1}, LinearRecurrence[{6, 42}, {6, 72}, 20]] (* Harvey P. Dale, Mar 25 2015 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Philippe Deléham, Dec 31 2007
EXTENSIONS
Corrected and extended by Harvey P. Dale, Mar 25 2015
STATUS
approved