OFFSET
0,3
LINKS
Walter Klotz and Torsten Sander, Some Properties of Unitary Cayley Graphs, The Electronic Journal of Combinatorics, Volume 14 (2007), #R45. See Corollary 7 p. 4.
FORMULA
a(n) = A058026(2*n+1). - Ridouane Oudra, Aug 20 2024
MAPLE
A070554:=proc(n) local p, a:=2*n+1; for p in numtheory[factorset](2*n+1) do a:=a*(1-2/p) end do; a end proc: seq(A070554(n), n=0..100); # Ridouane Oudra, Aug 20 2024
PROG
(PARI) a(n) = my(n = 2*n+1); n*prod(p=1, n, if (isprime(p) && !(n % p), (1-2/p), 1)); \\ Michel Marcus, Feb 02 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Nov 15 2000
EXTENSIONS
More terms from Sascha Kurz, Feb 02 2003
STATUS
approved