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A329584
phi(A327922(n))/4, for n >= 1, with phi = A000010 (Euler's totient).
1
1, 3, 2, 4, 3, 5, 7, 5, 6, 9, 6, 10, 6, 8, 13, 10, 9, 15, 9, 12, 11, 18, 10, 15, 16, 14, 22, 18, 15, 18, 24, 15, 25, 12, 27, 18, 28, 22, 18, 24, 20, 25, 21, 27, 18, 34, 23, 30, 28, 21, 37, 24, 30, 39, 26, 33, 20, 39, 27, 43, 30, 29, 45, 30, 36, 40, 27, 48
OFFSET
1,2
COMMENTS
This sequence applies to the odd m >= 3 numbers collected in A327922 with 4 dividing phi(2*m) = phi(m). The analog for even m is: every even numbers m >= 4 has even phi(2*m)/2 = A062570(m/2) = 2*A055034(m/2), This means that phi(2*m)/4 = A055034(m/2), for every even m >= 4.
FORMULA
a(n) = A000010(A327922(n))/4, for n >= 1.
EXAMPLE
n = 1: A327922(1) = 5, A000010(5) = 4, hence a(1) = 1.
n = 5: A327922(5) = 21 = 3*7, A000010(21) = 2*6 = 12, hence a(5) = 3.
MATHEMATICA
Select[EulerPhi[Range[3, 200, 2]]/4, IntegerQ] (* Amiram Eldar, Nov 17 2019 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Nov 17 2019
STATUS
approved