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Search: id:A147574
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| A147574 |
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Numbers with exactly 7 distinct prime divisors {2,3,5,7,11,13,17} |
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+0
5
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| 510510, 1021020, 1531530, 2042040, 2552550, 3063060, 3573570, 4084080, 4594590, 5105100, 5615610, 6126120, 6636630, 7147140, 7657650, 8168160, 8678670, 9189180, 10210200, 10720710, 11231220, 12252240, 12762750, 13273260, 13783770
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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 510510] == 92160 x, AppendTo[a, 510510 x]], {x, 1, 100}]; a (*Artur Jasinski*)
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CROSSREFS
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A060735, A143207, A147571-A147575, A147576-A147580
Sequence in context: A076337 A101036 A123321 this_sequence A046325 A136352 A138207
Adjacent sequences: A147571 A147572 A147573 this_sequence A147575 A147576 A147577
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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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