%I #42 Jul 26 2022 10:27:03

%S 1729,294409,1033669,1082809,1773289,5444489,7995169,8719309,17098369,

%T 19384289,23382529,26921089,37964809,43620409,45890209,50201089,

%U 69331969,84311569,105309289,114910489,146843929,168659569,172947529,180115489,188516329,194120389,214852609,228842209,230996949,246446929,271481329

%N Carmichael numbers ending in 9.

%C The first term is the Hardy-Ramanujan number.

%H Amiram Eldar, <a href="/A352970/b352970.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..109 from Chai Wah Wu)

%H <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers</a>.

%t Select[10*Range[0, 3*10^7] + 9, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* _Amiram Eldar_, May 28 2022 *)

%o (Python)

%o from itertools import islice

%o from sympy import factorint, nextprime

%o def A352970_gen(): # generator of terms

%o p, q = 3, 5

%o while True:

%o for n in range(p+11-((p+2) % 10),q,10):

%o f = factorint(n)

%o if max(f.values()) == 1 and not any((n-1) % (p-1) for p in f):

%o yield n

%o p, q = q, nextprime(q)

%o A352970_list = list(islice(A352970_gen(),5)) # _Chai Wah Wu_, May 11 2022

%Y Intersection of A002997 and A017377.

%Y Subsequence of A053181.

%Y Cf. A001235, A354609, A355305, A355307, A355309.

%K nonn,base

%O 1,1

%A _Omar E. Pol_, Apr 12 2022