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 A199427 #13 Aug 03 2014 14:01:35 %S A199427 1,7,10,13,22,28,43,58,70,73,127,148,160,163,190,202,238,253,262,307, %T A199427 322,352,370,400,433,472,475,493,517,532,535,568,598,637,673,685,688, %U A199427 742,832,847,853,862,898,940,955,1018,1087,1093,1102,1120,1183,1198,1270 %N A199427 Numbers n such that 4n+1 and 8n+3 are prime. %C A199427 According to Beiler: the integer 2 is a primitive root of all primes of the form 8n+3 provided 4n+1 is a prime. %D A199427 Albert H. Beiler: Recreations in the theory of numbers. New York: Dover, (2nd ed.) 1966, p. 102, nr. 4. %H A199427 Vincenzo Librandi, <a href="/A199427/b199427.txt">Table of n, a(n) for n = 1..10000</a> %F A199427 a(n) = intersection(A005098, A005124). %e A199427 For n = 1, both 11 and 5 are primes, hence 2 is a primitive root of 11. %t A199427 Select[Range[1270], PrimeQ[4*# + 1] && PrimeQ[8*# + 3] &] (* _T. D. Noe_, Nov 07 2011 *) %Y A199427 Cf. A001122, A005098, A005124. %K A199427 nonn %O A199427 1,2 %A A199427 _Martin Renner_, Nov 06 2011