This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A330446 #9 Dec 15 2019 08:36:40 %S A330446 140,1054,1068,4844,11209,19856,24949,28390,78184,423796,769516, %T A330446 4283544,5935168,13116053,122189752,441252296,528500308,636697392, %U A330446 669629030,669778082,1228748591 %N A330446 Composite numbers k such that 2^(k-1) == - lambda(k) (mod k), where lambda is the Carmichael lambda function (A002322). %C A330446 Composite numbers k such that A062173(k) = A277127(k). %C A330446 The odd terms are 11209, 24949, 13116053, ... %C A330446 Note that if p is an odd prime, then 2^(p-1) == - lambda(p) (mod p), because lambda(p) = p-1. %e A330446 140 is a term since it is composite and 2^(140-1) == 140 - lambda(140) == 128 (mod 140). %t A330446 Select[Range[10^6], CompositeQ[#] && PowerMod[2, # - 1, #] == # - CarmichaelLambda[#] &] %Y A330446 Cf. A002322, A062173, A277127. %K A330446 nonn,more %O A330446 1,1 %A A330446 _Amiram Eldar_ and _Thomas Ordowski_, Dec 15 2019