A140234 - OEIS

%I #4 May 24 2021 15:48:18

%S 0,0,0,0,4,4,10,10,10,19,29,29,29,29,43,58,58,58,58,58,58,79,101,101,

%T 101,126,152,152,152,152,152,152,152,185,219,254,254,254,292,331,331,

%U 331,331,331,331,331,377,377,377,426,426,477,477,477,477,532,532,589

%N Sum of the semiprimes <= n.

%C This is to semiprimes A001358 as A034387 is to primes A000040. From the prime number theorem A034387(n) has the asymptotic expression: a(n) ~ n^2 / (2 log n), so what is the asymptotic expression for a(n)?

%F a(n) = Sum_{j such that j is in A001358 and j<=n} = A062198(A072000(n)).

%Y Cf. A001358, A034387, A051352, A062198, A072000, A100959, A140235.

%K easy,nonn

%O 0,5

%A _Jonathan Vos Post_, May 13 2008