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 A057872 #12 May 13 2013 01:54:05
%S A057872 0,0,1,2,2,3,3,5,5,5,5,8,8,10,10,10,10,13,13,16,16,16,16,19,19,19,19,
%T A057872 19,19,23,23,26,26,26,26,26,26,30,30,30,30,33,33,37,37,37,37,41,41,41,
%U A057872 41,41,41,45,45,45,45,45,45,49,49,53,53,53,53,53,53,57,57,57,57,62,62,66,66,66,66
%N A057872 A version of the Chebyshev function theta(n): a(n) = round(Sum_{primes p <= n } log(p)).
%C A057872 See A035158, which is the main entry for this function.
%C A057872 The old entry with this sequence number was a duplicate of A053632.
%D A057872 G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 340.
%D A057872 D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, Section VII.35, p. 267.
%H A057872 Charles R Greathouse IV, <a href="/A057872/b057872.txt">Table of n, a(n) for n = 0..10000</a>
%F A057872 theta(n) = log(A034386(n)).
%F A057872 a(n) ~ n, a statement equivalent to the Prime Number Theorem. - _Charles R Greathouse IV_, Sep 23 2012
%o A057872 (PARI) v=List(); t=0; for(n=0, 100, if(isprime(n), t+=log(n)); listput(v, round(t))); Vec(v) \\ _Charles R Greathouse IV_, Sep 23 2012
%Y A057872 Cf. A034386, A215259, A215260.
%K A057872 nonn
%O A057872 0,4
%A A057872 _N. J. A. Sloane_, Oct 02 2008