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 A100709 #6 Mar 30 2012 16:50:06 %S A100709 1001,3004,1502,751,2254,1127,3382,1691,5074,2537,7612,3806,1903,5710, %T A100709 2855,8566,4283,12850,6425,19276,9638,4819,14458,7229,21688,10844, %U A100709 5422,2711,8134,4067,12202,6101,18304,9152,4576,2288,1144,572,286,143,430,215,646 %N A100709 Trajectory of 1001 under "3x+1" map. %D A100709 V. Klee and S. Wagon, Unsolved Problems, Math. Assoc. America, 1991, p. 191. %H A100709 T. D. Noe, <a href="/A100709/b100709.txt">Table of n, a(n) for n=0..142</a> %Y A100709 Cf. A006370. %K A100709 nonn %O A100709 0,1 %A A100709 _N. J. A. Sloane_, Apr 10 2006