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A147575
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Numbers with exactly 8 distinct prime divisors {2,3,5,7,11,13,17,19}.
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12
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9699690, 19399380, 29099070, 38798760, 48498450, 58198140, 67897830, 77597520, 87297210, 96996900, 106696590, 116396280, 126095970, 135795660, 145495350, 155195040, 164894730, 174594420, 184294110, 193993800, 203693490, 213393180, 232792560, 242492250, 252191940
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OFFSET
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1,1
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COMMENTS
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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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LINKS
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Amiram Eldar, Table of n, a(n) for n = 1..10000
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FORMULA
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a(n) = 9699690 * A080682(n). - Amiram Eldar, Mar 10 2020
Sum_{n>=1} 1/a(n) = 1/1658880. - Amiram Eldar, Nov 12 2020
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MATHEMATICA
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a = {}; Do[If[EulerPhi[9699690 x] == 1658880 x, AppendTo[a, 9699690 x]], {x, 1, 100}]; a
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CROSSREFS
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Cf. A060735, A080682, A143207, A147571-A147575, A147576-A147580.
Sequence in context: A348072 A123322 A258363 * A046326 A154573 A058332
Adjacent sequences: A147572 A147573 A147574 * A147576 A147577 A147578
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski, Nov 07 2008
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EXTENSIONS
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More terms from Amiram Eldar, Mar 10 2020
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STATUS
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approved
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