A057685 - OEIS

%I #17 Dec 12 2023 15:54:54

%S 19,362,181,3440,1720,860,430,215,43,818,409,7772,3886,1943,36918,

%T 18459,6153,2051,293,5568,2784,1392,696,348,174,87,29,552,276,138,69,

%U 23,438,219,73,1388,694,347,6594,3297,1099,157,2984,1492,746

%N Trajectory of 19 under the `19x+1' map.

%C See A057684 for definition.

%H T. D. Noe, <a href="/A057685/b057685.txt">Table of n, a(n) for n=0..72</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,1).

%t Px1[p_,n_]:=Catch[For[i=1,i<PrimePi[p],i++,If[Divisible[n,Prime[i]],Throw[n/Prime[i]]]];p*n+1];

%t NestList[Px1[19,#]&,19,100] (* _Paolo Xausa_, Dec 10 2023 *)

%Y Cf. A057446, A057216, A057522, A057534, A057614. See also A033478, A057688, A057684, A057685, A057686, A057687, A057689, A057690, A057691.

%K nonn,easy

%O 0,1

%A _N. J. A. Sloane_, Oct 20 2000