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 A058871 #4 Sep 30 2012 01:33:13
%S A058871 1,3,5,7,9,13,18,20,23,25,29,48,55,98,117,119,123,130,173,187,193,198,
%T A058871 205,213,218,223,248,249,255,259,265,268,285,292,299,311,329,346,351,
%U A058871 386,390,393,397,411,412,448,483,487,513,515,525,554,563,574,587,597
%N A058871 Sum of next n primes (A007468) is prime for odd n or half the sum is prime for even n.
%t A058871 Do[ s = Sum[ Prime[i], {i, n(n-1)/2 + 1, n(n+1)/2} ]; If[ PrimeQ[s] || PrimeQ[s/2], Print[n] ], {n, 10^3} ]
%Y A058871 Cf. A007468.
%K A058871 nonn
%O A058871 1,2
%A A058871 _Robert G. Wilson v_, Jan 06 2001