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 A087251 #4 Oct 15 2013 22:32:16 %S A087251 1,2,16,4,52,8,40,160,88,20,64,24,9232,32,100,112,304,196,136,48,148, %T A087251 232,56,184,68,208,72,340,808,80,244,84,256,592,280,96,448,104,520, %U A087251 116,352,628,4372,128,132,400,916,424,144,1024,152,472,736,168,176,532,180 %N A087251 Distinct largest-peak-values in 3x+1 trajectory arranged by their first appearance as initial value increases. A025586 without repetitions while keeping order. %e A087251 peak=160 appears in trajectory started with n=15 and %e A087251 before peaks = 1,2,16,4,52,8,40 appear at n=1,..,14 %e A087251 initial values: 160=a(8), the 8th new peak-value. %Y A087251 Cf. A025586. %K A087251 nonn %O A087251 1,2 %A A087251 _Labos Elemer_, Sep 08 2003