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 A158662 #6 Feb 27 2017 17:30:32
%S A158662 1,3,6,6,11,11,18,18,18,18,29,29,42,42,42,42,59,59,78,78,78,78,101,
%T A158662 101,101,101,101,101,130,130,161,161,161,161,161,161,198,198,198,198,
%U A158662 239,239,282,282,282,282,329,329,329,329,329,329
%N A158662 Sum of primes <= n if 1 is counted as a prime.
%C A158662 a(n) = A034387(n) + 1. a(p) - a(p-1) = p, for p = primes (A000040), a(c) - a(c-1) = 0, for c = composite numbers (A002808).
%H A158662 Harvey P. Dale, <a href="/A158662/b158662.txt">Table of n, a(n) for n = 1..1000</a>
%t A158662 Module[{nn=60,c},c=Join[{1},Prime[Range[PrimePi[nn]]]];Table[Total[ Select[ c,#<=n&]],{n,nn}]] (* _Harvey P. Dale_, Jun 01 2014 *)
%t A158662 Accumulate[Join[{1},Table[If[PrimeQ[n],n,0],{n,60}]]] (* _Harvey P. Dale_, Feb 27 2017 *)
%Y A158662 Cf. A034387, A000040, A002808.
%K A158662 nonn
%O A158662 1,2
%A A158662 _Jaroslav Krizek_, Mar 23 2009, Apr 12 2009