A141427 a(n) = phi(A067775(n)).

1, 4, 10, 16, 22, 28, 30, 40, 46, 52, 58, 60, 70, 72, 82, 88, 100, 106, 112, 130, 136, 138, 148, 150, 156, 166, 172, 178, 180, 190, 196, 198, 210, 226, 232, 238, 240, 250, 256, 262, 268, 270, 280, 282, 292, 310, 316, 330, 336, 346, 352, 358, 366, 372, 382, 388

Offset: 1

Author

Giovanni Teofilatto, Aug 06 2008

Keywords

• nonn

Comments

Count of numbers smaller than and coprime to p for primes p such that p + 4 is composite.

Subsequence of A006093.

Crossrefs

Cf. A067775, A000010 (Euler totient function), A006093 (primes minus 1), A141426, A141515.

Programs

PARI

{forprime(p=2, 400, if(!isprime(p+4), print1(eulerphi(p), ",")))} \\ Klaus Brockhaus, Aug 31 2008

Extensions

More terms from Robert G. Wilson v, Aug 18 2008

Edited by N. J. A. Sloane and Klaus Brockhaus, Aug 31 2008