OFFSET
1,1
COMMENTS
All terms are composite.
4 is the only even term.
For odd primes p, 3*p is a term iff p is in A005384.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
Wikipedia, Carmichael function
EXAMPLE
25-lambda(25) = 25-20 = 5 is prime so 25 is in the sequence.
MAPLE
select(t -> isprime(t - numtheory:-lambda(t)), [$1..10000]);
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Nov 08 2016
STATUS
approved