OFFSET
1,8
REFERENCES
See A051664.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537 (terms 1..1000 from T. D. Noe)
FORMULA
From Benoit Cloitre, Aug 06 2003: (Start)
a(4n+2) = a(2n+1); a(4n) = a(2n) + phi(2n).
When p is an odd prime and m integer >= 1: a(p^m) = a(2*p^m) = p^m - p^(m-1) - p + 1. In particular a(p) = a(2p) = 0. (End)
MATHEMATICA
Table[Count[CoefficientList[Cyclotomic[n, x], x], _?(#==0&)], {n, 0, 100}]
PROG
(PARI) a(n)=sum(k=0, eulerphi(n), if(polcoeff(polcyclo(n), k), 0, 1))
(PARI) A086798(n) = (1 + eulerphi(n) - length(select(x->x!=0, Vec(polcyclo(n))))); \\ Antti Karttunen, Sep 21 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 05 2003
EXTENSIONS
More terms from Benoit Cloitre and T. D. Noe, Aug 06 2003
STATUS
approved