OFFSET
1,2
COMMENTS
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (0,6).
FORMULA
a(n) = (5 - (-1)^n)*6^(1/4*(2*n - 5 + (-1)^n)).
G.f.: x*(1+4*x)/(1-6*x^2).
a(n+3) = a(n+2)*a(n+1)/a(n). - Reinhard Zumkeller, Mar 04 2011
a(n) = ((1-(-1)^n)*sqrt(6)/2 + 2*(1+(-1)^n))*6^(n/2 -1). - G. C. Greubel, Jul 16 2021
MATHEMATICA
LinearRecurrence[{0, 6}, {1, 4}, 40] (* G. C. Greubel, Jul 16 2021 *)
PROG
(Magma) [ n le 2 select 3*n-2 else 6*Self(n-2): n in [1..29] ];
(Sage) [((1 - (-1)^n)*sqrt(6)/2 + 2*(1 + (-1)^n))*6^(n/2 -1) for n in (1..40)] # G. C. Greubel, Jul 16 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Aug 15 2009
STATUS
approved