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 A156780 #3 Jul 14 2012 11:32:24
%S A156780 0,0,2,10,10,30,30,68,68,68,68,140,140,246,246,246,246,406,406,616,
%T A156780 616,616,616,900,900,900,900,900,900,1290,1290,1760,1760,1760,1760,
%U A156780 1760,1760,2364,2364,2364,2364,3094,3094,3934,3934,3934,3934,4920,4920,4920
%N A156780 sp(n)*pi(n) = A034387(n)*A000720(n) = (sum of primes <= n)*(number of primes <= n).
%C A156780 All terms are even, since the parity of sp(n)=A034387(n) is always the opposite of pi(n)=A000720(n). Indeed, both change by an odd amount at each prime, starting with the first nonzero values sp(2)=2 and pi(2)=1. Thus one might also consider the integer sequence a(n)/2 = 0, 0, 1, 5, 5, 15, 15, 34, 34, 34, 34, 70, 70, 123, 123, 123, 123, 203, 203, 308,.... Sequence A156778 lists these values (without duplicates).
%F A156780 a(n) = 2*A156778( pi(n)), where pi(n) = A000720(n)= PrimePi(n) = #{primes <= n}.
%o A156780 (PARI) vector(80,n,sum(i=1,primepi(n),prime(i))*primepi(n))
%K A156780 nonn
%O A156780 0,3
%A A156780 _M. F. Hasler_, Feb 21 2009