A269452 phi(A157352(n)), n >= 1, where phi is Euler's totient function A000010, and A157352 gives the products of two distinct safe primes.

24, 40, 60, 88, 132, 184, 220, 232, 276, 348, 328, 460, 424, 492, 580, 636, 664, 712, 820, 1012, 904, 996, 1060, 1068, 1048, 1276, 1356, 1384, 1432, 1660, 1572, 1804, 1528, 1780, 1864, 1912, 2076, 2332, 2260, 2148, 2008, 2292, 2668, 2248, 2620, 2344, 2796, 2868, 3012, 2872, 3460, 3652, 3772, 3372

Offset

1,1

Comments

phi(p*q) = (p-1)(q-1) where p, q are distinct safe primes.

2^(a(n)/2) == 1 (mod A157352(n)). For the reference see a comment on A269454. - Wolfdieter Lang, Mar 31 2016

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1500

Formula

a(n) = phi(A157352(n)), n >= 1.

Mathematica

EulerPhi /@ Select[Select[Range@ 4000, PrimeNu@ # == 2 &], Times @@ Map[If[PrimeQ[(# - 1)/2], #, 0] &, Map[First, FactorInteger@ #]] == # &] (* Michael De Vlieger, Feb 28 2016 *)

Crossrefs

Cf. A000010, A157352, A269454.

Sequence in context: A043119 A039296 A043899 * A294029 A366675 A195562

Adjacent sequences: A269449 A269450 A269451 * A269453 A269454 A269455

Keyword

nonn

Author

Marina Ibrishimova, Feb 27 2016

Extensions

More terms from Michael De Vlieger, Feb 28 2016

Status

approved