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A147579 Numbers with exactly 6 distinct odd prime divisors {3,5,7,11,13,17} +0
6
255255, 765765, 1276275, 1786785, 2297295, 2807805, 3318315, 3828825, 4339335, 5360355, 6381375, 6891885, 8423415, 8933925, 9954945, 11486475, 12507495, 13018005, 14039025, 16081065, 16591575, 19144125, 19654635, 20675655 (list; graph; listen)
OFFSET

1,1

COMMENT

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[255255 x] == 92160 x, AppendTo[a, 255255 x]], {x, 1, 100}]; a(*Artur Jasinski*)

CROSSREFS

A060735, A143207, A147571-A147575, A147576-A147580

Sequence in context: A069176 A140079 A034631 this_sequence A087025 A161534 A052197

Adjacent sequences: A147576 A147577 A147578 this_sequence A147580 A147581 A147582

KEYWORD

nonn

AUTHOR

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

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.


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