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Search: id:A141515
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| A141515 |
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a(n) = phi(A067774(n)) where phi is Euler totient function. |
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+0
3
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| 1, 6, 12, 18, 22, 30, 36, 42, 46, 52, 60, 66, 72, 78, 82, 88, 96, 102, 108, 112, 126, 130, 138, 150, 156, 162, 166, 172, 180, 192, 198, 210, 222, 228, 232, 240, 250, 256, 262, 270, 276, 282, 292, 306, 312, 316, 330, 336, 348, 352, 358, 366, 372, 378, 382, 388
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Count of numbers smaller than and coprime to p for primes p such that p + 2 is composite.
Subsequence of A006093.
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PROGRAM
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(PARI) {forprime(p=2, 400, if(!isprime(p+2), print1(eulerphi(p), ", ")))} [From Klaus Brockhaus, Aug 31 2008]
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CROSSREFS
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Cf A067774 (primes p such that p+2 is composite), A000010 (Euler totient function), A006093 (primes minus 1), A141426, A141427.
Sequence in context: A160594 A146538 A154373 this_sequence A037981 A044846 A037917
Adjacent sequences: A141512 A141513 A141514 this_sequence A141516 A141517 A141518
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KEYWORD
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nonn
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AUTHOR
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Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Aug 11 2008
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EXTENSIONS
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Edited and a(1) = 1, a(12) = 66 inserted by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Aug 31 2008
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