cp's OEIS Frontend

A225538 Let r(n) denote the reverse of n. For every n, consider the sequence n_1 = n + 1 + r(n+1), and for m >= 2, n_m = n_(m-1) + 1 + r(n_(m-1) + 1). a(n) is the least m for which n_m is a palindrome, or 0 if there is no such m.

%I A225538 #22 Sep 03 2018 23:00:02
%S A225538 1,1,1,1,2,2,2,2,3,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,
%T A225538 1,1,2,1,2,1,1,1,1,1,1,2,1,2,2,1,1,1,1,1,2,1,2,2,4,1,1,1,1,2,1,2,2,4,
%U A225538 7,1,1,1,2,1,2,2,4,7,10,1,1,2,1,2,2,4,7
%N A225538 Let r(n) denote the reverse of n. For every n, consider the sequence n_1 = n + 1 + r(n+1), and for m >= 2, n_m = n_(m-1) + 1 + r(n_(m-1) + 1). a(n) is the least m for which n_m is a palindrome, or 0 if there is no such m.
%C A225538 Conjecture: the least n's for which a(n) = 0 are 1895, 1985, 2894, 2984, 3893, and 3983. - _Peter J. C. Moses_, May 10 2013
%C A225538 See analogous numbers in A023108 for which the so-called Lychrel process "Reverse and Add!", apparently, never leads to a palindrome.
%H A225538 Peter J. C. Moses, <a href="/A225538/b225538.txt">Table of n, a(n) for n = 0..5000</a>
%e A225538 For n=8, 9 + 9 = 18, 19 + 91 = 110, 111 + 111 = 222 is a palindrome. Thus a(8)=3.
%Y A225538 Cf. A023108.
%K A225538 nonn,base
%O A225538 0,5
%A A225538 _Vladimir Shevelev_, May 10 2013