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a(n) is the smallest Carmichael number (A002997) with the n-th prime as its smallest prime divisor, or 0 if no such number exists.
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%I #27 Apr 22 2024 08:12:34

%S 561,1105,1729,75361,29341,162401,334153,1615681,3581761,399001,

%T 294409,252601,1152271,104569501,2508013,178837201,6189121,10267951,

%U 10024561,14469841,4461725581,985052881,19384289,23382529,3828001,90698401,84350561,6733693,17098369

%N a(n) is the smallest Carmichael number (A002997) with the n-th prime as its smallest prime divisor, or 0 if no such number exists.

%H Amiram Eldar, <a href="/A135720/b135720.txt">Table of n, a(n) for n = 2..1383</a> (calculated using data from Claude Goutier; terms 2..447 from Donovan Johnson, terms 448..615 from Max Alekseyev)

%H Claude Goutier, <a href="http://www-labs.iro.umontreal.ca/~goutier/OEIS/A055553/">Compressed text file carm10e22.gz containing all the Carmichael numbers up to 10^22</a>.

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

%e a(2) = 561 because the smallest prime divisor of 561 is 3 which is the second prime.

%Y Cf. A002997, A135717, A006931, A135719, A135721, A141705.

%K nonn

%O 2,1

%A _Artur Jasinski_, Nov 25 2007

%E Two missing terms and terms up to a(447) added by _Donovan Johnson_, Dec 25 2013

%E a(448)-a(615) in b-file from _Max Alekseyev_, Mar 11 2018

%E Escape clause added by _Jianing Song_, Dec 12 2021