A067932 Primes p such that p+3 == 0 (mod phi(p+3)).

3, 5, 13, 29, 61, 509, 1021, 4093, 16381, 1048573, 4194301, 16777213, 536870909, 19807040628566084398385987581, 83076749736557242056487941267521533, 5316911983139663491615228241121378301

Offset

1,1

Comments

phi(n) divides n iff n=1 or n=2^w*3^u for w>=1 and u>=0 (see A007694). Such an n can only have the form p+3 if n=6 or n is a power of 2. So the terms of the sequence are 3 and the primes of the form 2^n-3, listed in A050415.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..30

Mathematica

Prepend[Select[2^Range[2, 200]-3, PrimeQ], 3]

Crossrefs

Sequence in context: A295617 A290113 A238216 * A339155 A168314 A335562

Adjacent sequences: A067929 A067930 A067931 * A067933 A067934 A067935

Keyword

easy,nonn

Author

Benoit Cloitre, Feb 22 2002

Extensions

Edited and extended by Robert G. Wilson v, Feb 27 2002 and by Dean Hickerson, Mar 21 2002

Status

approved