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%I #19 Apr 21 2024 22:08:57
%S 5310721,2278677961,9593125081,29859667201,467593730289953281,
%T 98538479002618905601,146842414757227736821
%N Carmichael numbers (A002997) that are central polygonal numbers (A002061).
%C Also, Carmichael numbers of the form k^2 + k + 1.
%C Also, Carmichael numbers of the form k^2 - k + 1.
%C There are no other terms below 10^22.
%C Carmichael numbers m such that 4m - 3 is square. - _Thomas Ordowski_, Apr 30 2018
%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>.
%Y Intersection of A002997 and A002061.
%Y Cf. A265285, A265628.
%K nonn,more,hard
%O 1,1
%A _Max Alekseyev_, Apr 30 2018
%E a(6)-a(7) calculated using data from _Claude Goutier_ and added by _Amiram Eldar_, Apr 20 2024
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