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 A121820 #4 Mar 30 2012 18:49:45 %S A121820 1,3,5,7,9,15,16,20,28,43,76,83,118,150,164,190,377,597,801,889,1091, %T A121820 1561,1814,2601,3016,6253,7281,13005,15167,25607,27191,37126,39419, %U A121820 41357,62946,78155,83024,184383,702826,1146234,1203569,1595690,1871469 %N A121820 Numbers m such that greatest prime divisor of (m-th prime + 1) is 3. %C A121820 Or, position of 3 in A023509 Greatest prime divisor of n-th prime + 1. %t A121820 Select[Range[990000],FactorInteger[Prime[ # ]+1][[ -1,1]]==3&] %Y A121820 Cf. A023509. %K A121820 nonn %O A121820 1,2 %A A121820 _Zak Seidov_, Sep 09 2006 %E A121820 More terms from _Stefan Steinerberger_, May 18 2007