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 A141515 a(n) = phi(A067774(n)) where phi is Euler totient function. 2
 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; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Count of numbers smaller than and coprime to p for primes p such that p + 2 is composite. Subsequence of A006093. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..6970 MATHEMATICA EulerPhi[#]&@Select[Prime@Range@80, !PrimeQ[# + 2] &] (* Vincenzo Librandi, Feb 09 2018 *) PROG (PARI) {forprime(p=2, 400, if(!isprime(p+2), print1(eulerphi(p), ", ")))} \\ Klaus Brockhaus, Aug 31 2008 (MAGMA) [EulerPhi(p): p in PrimesUpTo(400) | not IsPrime(p+2)]; // Vincenzo Librandi, Feb 09 2018 CROSSREFS Cf A067774 (primes p such that p+2 is composite), A000010 (Euler totient function), A006093 (primes minus 1), A141426, A141427. Sequence in context: A315732 A315733 A315734 * A315735 A315736 A315737 Adjacent sequences:  A141512 A141513 A141514 * A141516 A141517 A141518 KEYWORD nonn AUTHOR Giovanni Teofilatto, Aug 11 2008 EXTENSIONS Edited and a(1) = 1, a(12) = 66 inserted by Klaus Brockhaus, Aug 31 2008 STATUS approved

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Last modified November 21 00:36 EST 2018. Contains 317427 sequences. (Running on oeis4.)