OFFSET
1,3
COMMENTS
If n is a prime other than 5, then a(n) = n - 5 if n == 1 (mod 10), otherwise a(n) = n - 1. - Robert Israel, Jul 31 2017
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
m:=5; T:=[]: for n from 1 to 100 do S:={}: for a from 0 to n-1 do if gcd(a, n)=1 and gcd(cyclotomic(m, a), n)=1 then S:={op(S), a}: fi: od: T:=[op(T), nops(S)]: od: print(T):
MATHEMATICA
Table[Count[Range[n - 1], k_ /; And[CoprimeQ[k, n], CoprimeQ[Cyclotomic[5, k], n]]], {n, 70}] (* Michael De Vlieger, Jul 30 2017 *)
PROG
(PARI) a(n) = sum(k=0, n-1, (gcd(n, k)==1) && (gcd(n, polcyclo(5, k))==1)); \\ Michel Marcus, Jul 29 2017
CROSSREFS
KEYWORD
nonn,mult,easy
AUTHOR
Tristan Phillips, Jordan Lenchitz, Michael Mueller, Madison Wellen, Eric Jovinelly, Joshua Harrington, Jul 27 2017
STATUS
approved