OFFSET
1,2
COMMENTS
Agrees with independence number of the n-cube connected cycle graph for at least 3 <= n <= 8.
LINKS
Eric Weisstein's World of Mathematics, Cube-Connected Cycle Graph.
Eric Weisstein's World of Mathematics, Independence Number.
Index entries for linear recurrences with constant coefficients, signature (2,4,-8).
FORMULA
a(n) = 2^(n - 1) (n - mod(n, 2)).
a(n) = 2*a(n-1) + 4*a(n-2) - 8*a(n-3).
G.f.: (4 x^2)/((1 - 2 x)^2 (1 + 2 x)).
a(n) = 2^n*A004526(n). - R. J. Mathar, Mar 08 2021
Sum_{n>=2} 1/a(n) = (3/2)*log(4/3). - Amiram Eldar, Apr 22 2022
MATHEMATICA
Table[2^(n - 1) (n - Mod[n, 2]), {n, 20}]
LinearRecurrence[{2, 4, -8}, {0, 4, 8}, 20]
CoefficientList[Series[(4 x)/((1 - 2 x)^2 (1 + 2 x)), {x, 0, 20}], x]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Sep 06 2017
STATUS
approved