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 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 (list; graph; refs; listen; history; text; internal format)
 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 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 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

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Last modified December 6 06:14 EST 2021. Contains 349563 sequences. (Running on oeis4.)