A157756 - OEIS

A157756

Integers n such that by splitting their digits in two equal parts, the difference between the square of the first part and the second part eventually reaches 0 by iterating the process. If length is odd, split (length+1)/2, (length-1)/2.

%I #13 Apr 05 2020 23:27:06

%S 0,11,24,39,45,51,74,97,103,150,151,155,220,224,225,229,230,234,240,

%T 290,291,330,349,363,373,383,420,424,425,429,445,458,460,464,470,474,

%U 475,479,480,484,491,503,504,508,515,525,529,557,564,576,577,581,591

%N Integers n such that by splitting their digits in two equal parts, the difference between the square of the first part and the second part eventually reaches 0 by iterating the process. If length is odd, split (length+1)/2, (length-1)/2.

%C Example 3480 belongs to the sequence, because 34^2 - 80 = 1076 --> 10^2 - 76 = 24 --> 2^2 - 4 = 0.

%H Jean-Marc Falcoz, <a href="http://vargo.chez.com/upto1000.gif">Illustration of directed graph</a>, zoomable picture (up to 1000).

%H Jean-Marc Falcoz, <a href="http://vargo.chez.com/upto11000.txt">List of terms up to 11000</a>.

%K base,easy,nonn

%O 1,2

%A _Jean-Marc Falcoz_, Mar 06 2009