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A147578 Numbers with exactly 5 distinct odd prime divisors {3,5,7,11,13} 6
15015, 45045, 75075, 105105, 135135, 165165, 195195, 225225, 315315, 375375, 405405, 495495, 525525, 585585, 675675, 735735, 825825, 945945, 975975 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Successive numbers k such that EulerPhi[x]/x = m

( Family of sequences for successive n odd primes )

m=2/3 numbers with exactly 1 distinct prime divisor {3} see A000244

m=8/15 numbers with exactly 2 distinct prime divisors {3,5} see A033849

m=16/35 numbers with exactly 3 distinct prime divisors {3,5,7} see A147576

m=32/77 numbers with exactly 4 distinct prime divisors {3,5,7,11} see A147577

m=384/1001 numbers with exactly 5 distinct prime divisors {3,5,7,11,13} see A147578

m=6144/17017 numbers with exactly 6 distinct prime divisors {3,5,7,11,13,17} see A147579

m=3072/323323 numbers with exactly 7 distinct prime divisors {3,5,7,11,13,17,19} see A147580

m=110592/323323 numbers with exactly 8 distinct prime divisors {3,5,7,11,13,17,19,23} see A147581

MATHEMATICA

a = {}; Do[If[EulerPhi[x]/x == 384/1001, AppendTo[a, x]], {x, 1, 1000000}]; a(*Artur Jasinski*)

CROSSREFS

A060735, A143207, A147571-A147575, A147576-A147580

Sequence in context: A129485 A133778 A200090 * A205022 A151595 A187423

Adjacent sequences:  A147575 A147576 A147577 * A147579 A147580 A147581

KEYWORD

nonn

AUTHOR

Artur Jasinski (grafix(AT)csl.pl), Nov 07 2008

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Last modified February 16 13:02 EST 2012. Contains 205909 sequences.