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 A091554 #3 Mar 30 2012 17:22:32
%S A091554 7,11,13,17,19,23,31,53,59,73,79,89,97,103,109,113,137,139,149,157,
%T A091554 163,181,193,211,223,227,269,281,293,313,331,337,373,389,397,409,419,
%U A091554 421,433,463,467,487,499,509,521,523,541,547,571,599,601,617,631,641,643
%N A091554 Primes p such that k = 2p is the smallest positive solution to the equation sigma(p+k) = sigma(p) + sigma(k).
%C A091554 Note that for all primes p > 3, sigma(3p) = sigma(p) + sigma(2p).
%t A091554 lst={}; Do[p=Prime[n]; k=1; While[DivisorSigma[1, p+k]!=DivisorSigma[1, p]+DivisorSigma[1, k], k++ ]; If[k==2p, AppendTo[lst, p]], {n, 3, 200}]; lst
%Y A091554 Cf. A066435 (least k such that sigma(n+k)=sigma(n)+sigma(k)).
%K A091554 nonn
%O A091554 1,1
%A A091554 _T. D. Noe_, Jan 20 2004