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 A016040 #20 Jan 06 2021 22:56:24
%S A016040 0,1,3,5,7,10,13,16,19,22,26,29,33,37,40,44,49,53,57,61,65,70,74,79,
%T A016040 83,88,92,97,102,107,111,116,121,126,131,136,141,146,151,157,162,167,
%U A016040 172,177,183,188,193,199,204,210,215,221,226,232,237,243,248
%N A016040 Integer part of Chebyshev's theta function: floor( log(Product_{k=1..n} prime(k)) ).
%H A016040 R. J. Mathar, <a href="/A016040/b016040.txt">Table of n, a(n) for n = 1..1000</a>
%H A016040 J. W. Sander, <a href="http://www.jstor.org/stable/2974508">A story of binomial coefficients and primes</a>, Amer. Math. Monthly 102 (1995), 802-807.
%F A016040 a(n) = A000195(A002110(n)).
%F A016040 a(n) ~ n log n by the prime number theorem. - _Charles R Greathouse IV_, Dec 11 2008
%t A016040 Table[Floor[N[Sum[Log[Prime[x]], {x, 1, n}]]], {n, 1, 1000}] (* _Artur Jasinski_, Jan 23 2007 *)
%Y A016040 Cf. A035158.
%K A016040 nonn
%O A016040 1,3
%A A016040 _Robert G. Wilson v_
%E A016040 New name from _Charles R Greathouse IV_, Dec 11 2008