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Number of primes <= n-th Carmichael lambda number.
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%I #15 Sep 08 2022 08:46:17

%S 0,0,1,1,2,1,3,1,3,2,4,1,5,3,2,2,6,3,7,2,3,4,8,1,8,5,7,3,9,2,10,4,4,6,

%T 5,3,11,7,5,2,12,3,13,4,5,8,14,2,13,8,6,5,15,7,8,3,7,9,16,2,17,10,3,6,

%U 5,4,18,6,8,5,19,3,20,11,8,7,10,5,21,2

%N Number of primes <= n-th Carmichael lambda number.

%F a(n) = A000720(A002322(n)). - _Michel Marcus_, Nov 11 2016

%p with(numtheory):

%p a:= n-> pi(lambda(n)):

%p seq(a(n), n=1..100); # _Alois P. Heinz_, Nov 11 2016

%t Table[PrimePi[CarmichaelLambda[n]], {n, 100}]

%o (Magma) [0] cat [#PrimesUpTo(CarmichaelLambda(n)): n in [2..100]];

%Y Cf. A002322, A054782, A070804, A273974, A277062, A277063.

%K nonn

%O 1,5

%A _Vincenzo Librandi_, Nov 11 2016