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A039767 GCD(phi(a(n)),a(n)-1) = number of prime factors of (a(n)-1). 0
4, 6, 8, 10, 12, 14, 15, 18, 20, 24, 26, 27, 30, 32, 35, 38, 39, 42, 44, 48, 50, 51, 54, 55, 60, 62, 63, 68, 72, 74, 75, 80, 81, 82, 84, 87, 90, 95, 98, 99, 102, 104, 108, 110, 114, 119, 122, 123, 126, 128, 132, 135, 138, 140, 143, 147, 150, 152, 158, 159, 164, 168 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..62.

EXAMPLE

phi(15)=8, gcd(8,14)=2, 14=2*7, 2 prime factors.

CROSSREFS

Cf. A000010, A001221.

Sequence in context: A078942 A248419 A186389 * A176235 A201221 A185604

Adjacent sequences:  A039764 A039765 A039766 * A039768 A039769 A039770

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified January 20 02:29 EST 2018. Contains 297938 sequences.