OFFSET
1,1
COMMENTS
Quotients arising from this sequence give A034478 ((5^(n-1)+1)/2).
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..200
Index entries for linear recurrences with constant coefficients, signature (12,-20).
FORMULA
a(n) = 10^(n-1) + 2^(n-1).
G.f.: Q(0) where Q(k)= 1 + 5^k/(1 - 2*x/(2*x + 5^k/Q(k+1) )); (continued fraction ). - Sergei N. Gladkovskii, Apr 10 2013
G.f.: 2*x*(1-6*x)/((1-2*x)*(1-10*x)). - Vincenzo Librandi, Sep 12 2014
a(n) = 12*a(n-1) - 20*a(n-2) for n>1. - Vincenzo Librandi, Sep 12 2014
MATHEMATICA
CoefficientList[Series[2 (1 - 6 x)/((1 - 2 x) (1 - 10 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Sep 12 2014 *)
PROG
(Magma) [2^(n-1)+10^(n-1): n in [1..21]]; // Vincenzo Librandi, Sep 12 2014
(PARI) a(n) = 10^(n-1) + 2^(n-1) \\ Charles R Greathouse IV, Jun 11 2015
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Patrick De Geest, Jun 15 1999
STATUS
approved