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 A162002 #4 Jun 02 2012 06:36:46 %S A162002 1,2,3,4,5,6,8,10,12,14,15,16,17,18,20,24,26,28,30,32,34,36,40,42,43, %T A162002 44,46,48,51,52,56,58,60,64,68,70,72,76,78,80,84,85,88,90,96,100,102, %U A162002 104,112,120,124,126,127,128,130,132,136,140,141,144,145,148,156,160,164 %N A162002 Numbers n for which 2^^n == 2^2^n (mod n); for the "^^" notation see A092188. %H A162002 Robert Munafo, <a href="http://www.mrob.com/pub/math/seq-a162002.html">2^^N == 2^(2^N) mod N</a> %e A162002 3 is in the sequence because 2^2^3 = 2^8 = 256 == 1 mod 3, and 2^^3 = 2^2^2 = 2^4 = 16 == 1 mod 3. %Y A162002 Cf. A092188, A162018, A014221 %K A162002 easy,nonn %O A162002 1,2 %A A162002 _Robert Munafo_, Jun 24 2009