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%I #20 Feb 05 2024 17:23:14
%S 1,3,10,15,18,28,63,90,140,156,234,260,315,364,408,510,528,585,672,
%T 680,684,819,880,1120,1248,1920,2080,2912,3420,6120,6528,6660,7140,
%U 7920,8400,8568,8892,9324,9840,10710,10880,11088,11424,13260
%N Numbers k such that lambda(k) = tau(k).
%C Lambda(n) is the Carmichael lambda function (A002322). tau(n) or sigma_0(n), the number of divisors of n (A000005).
%H Amiram Eldar, <a href="/A173600/b173600.txt">Table of n, a(n) for n = 1..1000</a>
%e 2912 is in the sequence because lambda(2912) = tau(2912) = 24.
%p with(numtheory):for n from 1 to 15000 do: if lambda(n)=tau(n) then printf(`%d,
%p `, n):else fi:od:
%t Select[Range[10^4], CarmichaelLambda[#] == DivisorSigma[0, #] &] (* _Amiram Eldar_, Jul 15 2019 *)
%o (PARI) isok(n) = numdiv(n) == lcm(znstar(n)[2]) \\ _Miles Englezou_, Feb 05 2024
%Y Cf. A000005, A002322.
%K nonn
%O 1,2
%A _Michel Lagneau_, Nov 23 2010
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