OFFSET
1,1
COMMENTS
This sequence includes all the Carmichael numbers (A002997).
Prime p divides 3^p - 2^p - 1. Quotients (3^p - 2^p - 1)/p, where p = prime(n), are listed in A127071.
Numbers k such that k divides 3^k - 2^k - 1 are listed in A127072.
Pseudoprimes in A127072 include all the powers of the primes {2, 3, 7}.
Numbers k such that k^2 divides 3^k - 2^k - 1 are listed in A127074.
Numbers k such that k^3 divides 3^k - 2^k - 1 are 1, 4, 7, ...
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Carmichael number.
Eric Weisstein's World of Mathematics, Pseudoprime.
MATHEMATICA
Select[Select[Range[2^15], !PrimeQ[ # ]&&IntegerQ[(3^#-2^#-1)/# ]&], !IntegerQ[Log[2, # ]]&&!IntegerQ[Log[3, # ]]&&!IntegerQ[Log[7, # ]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Jan 04 2007
STATUS
approved