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m-th composite number c(m) = A002808(m), where m is the n-th prime number: a(n) = A002808(A000040(n)).
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%I #17 Jan 03 2022 02:55:57

%S 6,8,10,14,20,22,27,30,35,44,46,54,58,62,66,75,82,85,92,96,99,108,114,

%T 120,129,134,136,142,144,148,166,171,178,182,194,196,204,210,215,221,

%U 230,232,245,247,252,254,268,285,289,291,296,302,304,318,324,330,338

%N m-th composite number c(m) = A002808(m), where m is the n-th prime number: a(n) = A002808(A000040(n)).

%C Composites (A002808) with prime (A000040) subscripts. a(n) U A175251(n) = A002808(n). Subsequence of A022449 (composites (A002808) with noncomposite (A008578) subscripts), a(n) = A022449(n+1). - _Jaroslav Krizek_, Mar 14 2010

%t Composite[n_] := FixedPoint[n + PrimePi[#] + 1 & , n + PrimePi[n] + 1];

%t a[n_] := Composite[Prime[n]];

%t Array[a, 100] (* _Jean-François Alcover_, Jan 26 2018, after _Robert G. Wilson v_ *)

%Y Cf. A002808, A000040, A008578, A022449, A065856, A065857, A175251.

%K nonn

%O 1,1

%A _Labos Elemer_, Nov 26 2001