

A278021


Numbers n such that n  lambda(n) is prime, where lambda = A002322.


2



4, 9, 15, 25, 33, 35, 49, 65, 69, 77, 87, 91, 95, 115, 119, 121, 123, 143, 159, 169, 185, 187, 215, 221, 247, 249, 255, 259, 267, 287, 289, 295, 299, 319, 323, 329, 339, 341, 361, 365, 377, 393, 395, 407, 413, 415, 427, 437, 455, 473, 485, 511, 515, 519
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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


FORMULA

A010051(n  A002322(n)) = 1.


EXAMPLE

25lambda(25) = 2520 = 5 is prime so 25 is in the sequence.


MAPLE

select(t > isprime(t  numtheory:lambda(t)), [$1..10000]);


CROSSREFS

Cf. A002322, A005384, A010051, A277127.
Contains A001248. Contained in union of A001248 and A024556.
Sequence in context: A109641 A134675 A050530 * A102084 A193315 A030664
Adjacent sequences: A278018 A278019 A278020 * A278022 A278023 A278024


KEYWORD

nonn


AUTHOR

Robert Israel, Nov 08 2016


STATUS

approved



