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 A140234 #8 Jul 06 2025 21:38:01
%S A140234 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 A140234 101,126,152,152,152,152,152,152,152,185,219,254,254,254,292,331,331,
%U A140234 331,331,331,331,331,377,377,377,426,426,477,477,477,477,532,532,589
%N A140234 Sum of the semiprimes <= n.
%C A140234 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 A140234 a(n) = Sum_{j such that j is in A001358 and j<=n} = A062198(A072000(n)).
%t A140234 a[n_]:=Total[Select[Range[n],PrimeOmega[#]==2&]];Array[a,58,0] (* _James C. McMahon_, Jul 06 2025 *)
%Y A140234 Cf. A001358, A034387, A051352, A062198, A072000, A100959, A140235.
%K A140234 easy,nonn
%O A140234 0,5
%A A140234 _Jonathan Vos Post_, May 13 2008