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A352970 Carmichael numbers ending in 9.

%I A352970 #42 Jul 26 2022 10:27:03
%S A352970 1729,294409,1033669,1082809,1773289,5444489,7995169,8719309,17098369,
%T A352970 19384289,23382529,26921089,37964809,43620409,45890209,50201089,
%U A352970 69331969,84311569,105309289,114910489,146843929,168659569,172947529,180115489,188516329,194120389,214852609,228842209,230996949,246446929,271481329
%N A352970 Carmichael numbers ending in 9.
%C A352970 The first term is the Hardy-Ramanujan number.
%H A352970 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 A352970 <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers</a>.
%t A352970 Select[10*Range[0, 3*10^7] + 9, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* _Amiram Eldar_, May 28 2022 *)
%o A352970 (Python)
%o A352970 from itertools import islice
%o A352970 from sympy import factorint, nextprime
%o A352970 def A352970_gen(): # generator of terms
%o A352970     p, q = 3, 5
%o A352970     while True:
%o A352970         for n in range(p+11-((p+2) % 10),q,10):
%o A352970             f = factorint(n)
%o A352970             if max(f.values()) == 1 and not any((n-1) % (p-1) for p in f):
%o A352970                 yield n
%o A352970         p, q = q, nextprime(q)
%o A352970 A352970_list = list(islice(A352970_gen(),5)) # _Chai Wah Wu_, May 11 2022
%Y A352970 Intersection of A002997 and A017377.
%Y A352970 Subsequence of A053181.
%Y A352970 Cf. A001235, A354609, A355305, A355307, A355309.
%K A352970 nonn,base
%O A352970 1,1
%A A352970 _Omar E. Pol_, Apr 12 2022