OFFSET
1,2
COMMENTS
Sequence consists of all numbers with binary representation 1(011)*.
LINKS
Colin Barker, Table of n, a(n) for n = 1..1001
Index entries for linear recurrences with constant coefficients, signature (9,-8).
FORMULA
a(n) = 1(011)^(n-1) in binary representation.
a(n) = (5*8^n - 12)/28. - Giovanni Resta, Apr 25 2020
From Colin Barker, Apr 25 2020: (Start)
G.f.: x*(1 + 2*x) / ((1 - x)*(1 - 8*x)).
a(n) = 9*a(n-1) - 8*a(n-2) for n>2.
(End)
EXAMPLE
MATHEMATICA
a[n_] := (5*8^n - 12)/28; Array[a, 20] (* Giovanni Resta, Apr 25 2020 *)
PROG
(PARI) Vec(x*(1 + 2*x) / ((1 - x)*(1 - 8*x)) + O(x^20)) \\ Colin Barker, Apr 25 2020
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Reinhard Muehlfeld, Jul 27 2014
EXTENSIONS
More terms from Giovanni Resta, Apr 25 2020
STATUS
approved