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 A057685 #17 Dec 12 2023 15:54:54 %S A057685 19,362,181,3440,1720,860,430,215,43,818,409,7772,3886,1943,36918, %T A057685 18459,6153,2051,293,5568,2784,1392,696,348,174,87,29,552,276,138,69, %U A057685 23,438,219,73,1388,694,347,6594,3297,1099,157,2984,1492,746 %N A057685 Trajectory of 19 under the `19x+1' map. %C A057685 See A057684 for definition. %H A057685 T. D. Noe, <a href="/A057685/b057685.txt">Table of n, a(n) for n=0..72</a> %H A057685 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,1). %t A057685 Px1[p_,n_]:=Catch[For[i=1,i<PrimePi[p],i++,If[Divisible[n,Prime[i]],Throw[n/Prime[i]]]];p*n+1]; %t A057685 NestList[Px1[19,#]&,19,100] (* _Paolo Xausa_, Dec 10 2023 *) %Y A057685 Cf. A057446, A057216, A057522, A057534, A057614. See also A033478, A057688, A057684, A057685, A057686, A057687, A057689, A057690, A057691. %K A057685 nonn,easy %O A057685 0,1 %A A057685 _N. J. A. Sloane_, Oct 20 2000