OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
G. Fici, A Characterization of Bispecial Sturmian Words, MFCS 2012, Lecture Notes in Comput. Sci. 7464: 383-394 (2012)
FORMULA
a(n) = 2*(n+1) - phi(n+2).
MAPLE
with(numtheory); A180444:=n->`if`(n=0, 1, 2*(n+1) - phi(n+2)); seq(A180444(n), n=0..50); # Wesley Ivan Hurt, Apr 19 2014
MATHEMATICA
f[n_] := 2 n + 2 - EulerPhi[n + 2]; Array[f, 70, 0] (* Robert G. Wilson v, Sep 07 2010 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Fred Lunnon, Sep 05 2010
EXTENSIONS
More terms from Robert G. Wilson v, Sep 07 2010
STATUS
approved