A309123 - OEIS

%I #12 Jul 14 2019 18:01:30

%S 50,71,267,517,2274,1508,3884,1971,444,667,817,286,535,732,856,2926,

%T 541,736,858,293,542,233,483,695,834,2888,16995,41225,20304,4506,6713,

%U 2591,5091,22564,47502,21795,46686,21607,46484,215602,46433,68142,261041,510922

%N a(1) = 50 and for any n > 0, a(n+1)^2 is the smallest square that begins with a(n).

%C This sequence is similar to A308055.

%C The initial value (50) seems to be the first one for which the iteration of A018796 diverges; there are neither duplicates nor squares among the first 79000 terms.

%H Rémy Sigrist, <a href="/A309123/b309123.txt">Table of n, a(n) for n = 1..1000</a>

%H Rémy Sigrist, <a href="/A309123/a309123.gp.txt">PARI program for A309123</a>

%F a(1) = 50 and then a(n+1) = A018796(a(n)) for n > 0.

%e The first terms, alongside the square of a(n+1), are:

%e   n   a(n)  a(n+1)^2

%e   --  ----  --------

%e    1    50      5041

%e    2    71     71289

%e    3   267    267289

%e    4   517   5171076

%e    5  2274   2274064

%e    6  1508  15085456

%e    7  3884   3884841

%e    8  1971    197136

%e    9   444    444889

%e   10   667    667489

%e   11   817     81796

%e   12   286    286225

%e   13   535    535824

%e   14   732    732736

%e   15   856   8561476

%e   16  2926    292681

%o (PARI) See Links section.

%Y Cf. A018796, A308055.

%K nonn,base

%O 1,1

%A _Rémy Sigrist_, Jul 13 2019