A307713 a(n) = A000010(A307712(n))/A048865(A307712(n)).

2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 3, 2, 2, 2, 4, 4, 2, 2, 3, 4, 2, 3, 3, 4, 2, 3, 4, 2, 2, 2, 5, 2, 4, 5, 5, 3, 3, 3, 2, 3, 2, 4, 2, 3, 6, 3, 4, 4, 2, 6, 3, 6, 6, 6, 4, 3, 2, 6, 6, 3, 3, 6, 6, 7, 3, 3, 6, 4, 6, 3, 6, 7, 2, 6, 4, 3, 6, 4, 4, 4, 4, 5, 3, 7, 4, 2, 8, 4, 4, 4, 4, 4, 3, 4, 5, 6

Offset

1,1

Comments

1/a(n) is the fraction of primes in the reduced residue system mod A307712(n).

Links

Robert Israel, Table of n, a(n) for n = 1..600

Example

a(3) = 2 because A307712(3) = 5 and 1/2 of the reduced residue system mod 5 are primes.

Maple

g:=  proc(n) uses numtheory;
local v;
v:= phi(n)/(pi(n) - nops(factorset(n)));
if v::integer then v fi;
end proc:
map(g, [$3..40000]);

Mathematica

Select[Table[EulerPhi[n]/Count[Prime@ Range@ PrimePi@ n, _?(GCD[#, n] == 1 &)], {n, 3, 25000}], IntegerQ] (* Michael De Vlieger, Apr 23 2019 *)

Crossrefs

Cf. A000010, A048865, A307711, A307712.

Sequence in context: A037968 A303378 A074908 * A328680 A256707 A151963

Adjacent sequences: A307710 A307711 A307712 * A307714 A307715 A307716

Keyword

nonn

Author

Robert Israel, Apr 23 2019

Status

approved