OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..630
Index entries for linear recurrences with constant coefficients, signature (52,-624,1728).
FORMULA
From R. J. Mathar, Sep 24 2008: (Start)
a(n) = 81*36^(n-2) + 4^(n-2) - 18*12^(n-2).
G.f.: x*(1+12*x)/((1-4*x)*(1-12*x)*(1-36*x)). (End)
a(n) = A016129(n-1)^2. - Philippe Deléham, Nov 26 2008
a(n) = 4^(n-2) * (3^n - 1)^2. - Harvey P. Dale, Apr 15 2020
E.g.f.: (1/16)*exp(4*x)*(1 - 2*exp(8*x) + exp(32*x)). - G. C. Greubel, Oct 03 2024
MATHEMATICA
Table[(6^n-2^n)^2/16, {n, 20}] (* Harvey P. Dale, Apr 15 2020 *)
PROG
(Magma) [4^(n-2)*(3^n-1)^2: n in [1..30]]; // G. C. Greubel, Oct 03 2024
(SageMath) [4^(n-2)*(3^n-1)^2 for n in range(1, 31)] # G. C. Greubel, Oct 03 2024
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Al Hakanson (hawkuu(AT)gmail.com), Sep 22 2008
EXTENSIONS
More terms from R. J. Mathar, Sep 24 2008
STATUS
approved