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Search: id:A147572
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| A147572 |
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Numbers with exactly 5 distinct prime divisors {2,3,5,7,11} |
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+0
5
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| 2310, 4620, 6930, 9240, 11550, 13860, 16170, 18480, 20790, 23100, 25410, 27720, 32340, 34650, 36960, 41580, 46200, 48510, 50820, 55440, 57750, 62370, 64680, 69300, 73920, 76230, 80850, 83160, 92400, 97020
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Successive numbers k such that EulerPhi[x]/x = m
( Family of sequences for successive n primes )
m=1/2 numbers with exactly 1 distinct prime divisor {2} see A000079
m=1/3 numbers with exactly 2 distinct prime divisors {2,3} see A033845
m=4/15 numbers with exactly 3 distinct prime divisors {2,3,5} see A143207
m=8/35 numbers with exactly 4 distinct prime divisors {2,3,5,7} see A147571
m=16/77 numbers with exactly 5 distinct prime divisors {2,3,5,7,11} see A147572
m=192/1001 numbers with exactly 6 distinct prime divisors {2,3,5,7,11,13} see A147573
m=3072/17017 numbers with exactly 7 distinct prime divisors {2,3,5,7,11,13,17} see A147574
m=55296/323323 numbers with exactly 8 distinct prime divisors {2,3,5,7,11,13,17,19} see A147575
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MATHEMATICA
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a = {}; Do[If[EulerPhi[x]/x == 16/77, AppendTo[a, x]], {x, 1, 100000}]; a (*Artur Jasinski*)
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CROSSREFS
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A060735, A143207, A147571-A147575, A147576-A147580
Adjacent sequences: A147569 A147570 A147571 this_sequence A147573 A147574 A147575
Sequence in context: A046387 A136154 A076252 this_sequence A046303 A046403 A087978
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Nov 07 2008
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