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 A109723 #13 Jan 31 2019 03:27:29
%S A109723 2,10,28,58,100,160,238,328,440,568,712,874,1060,1264,1480,1720,1988,
%T A109723 2276,2584,2914,3266,3638,4028,4438,4888,5350,5830,6338,6870,7418,
%U A109723 7982,8582,9206,9854,10538,11240,11966,12718,13490,14288,15116,15968,16840
%N A109723 Sum of the first 2n+1 primes.
%C A109723 Bisection of A007504.
%H A109723 Ray Chandler, <a href="/A109723/b109723.txt">Table of n, a(n) for n = 0..10000</a>
%F A109723 a(n) = A007504(2n+1).
%t A109723 f[n_] := Sum[Prime[k], {k, n}]; Table[f[2n + 1], {n, 0, 42}]
%t A109723 Take[Accumulate[Prime[Range[160]]], {1,160,2}] (* _Harvey P. Dale_, Jan 11 2011 *)
%o A109723 (PARI) a(n) = sum(k=1, 2*n+1, prime(k)); \\ _Michel Marcus_, Jan 31 2019
%Y A109723 Cf. A007504, A109722, A109724, A109725, A109726.
%K A109723 easy,nonn
%O A109723 0,1
%A A109723 _Giovanni Teofilatto_, Aug 10 2005
%E A109723 Edited and extended by _Ray Chandler_, Aug 11 2005