A329584 - OEIS

A329584

phi(A327922(n))/4, for n >= 1, with phi = A000010 (Euler's totient).

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

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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.

LINKS

Table of n, a(n) for n=1..68.

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

Cf. A000010, A055034, A062570, A327922.

Sequence in context: A243852 A373701 A025532 * A335507 A372826 A195459

Adjacent sequences: A329581 A329582 A329583 * A329585 A329586 A329587

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang, Nov 17 2019

STATUS

approved