A162151 - OEIS

%I #3 Mar 30 2012 18:49:10

%S 12,18,24,27,36,45,48,132,144,156,198,264,276,288,291,297,372,375,396,

%T 405,492,495,528,576,1089,1212,1236,1287,1356,1359,1452,1572,1584,

%U 1629,1683,1728,1812,1818,2002,2067,2079,2178,2304,2424,2532,2676,2721,2727

%N Numbers n such that m=TITO(n)>n and TITO(m)=n, where TITO() = A161594().

%C Or, numbers that end in two-cycles under TITO operation.

%H Zak Seidov, <a href="http://zak08.livejournal.com/12876.html">141 pairs {n,m} for n<30000</a>

%H T. Khovanova, <a href="http://blog.tanyakhovanova.com/?p=144">Turning Numbers Inside Out</a> [From _Tanya Khovanova_, Jul 07 2009]

%F m=A161594(n)>n, and A161594(m)=n.

%e For smaller n's, m is a reversal of n, but for larger n's, there are other cases as well:{12,21},{18,81},{24,42},{27,72},...,{291,732},...,{372,651}, etc.

%Y Cf. A161594, A161597, A161598, A161600, A161730, A161732.

%K nonn,base

%O 1,1

%A _Zak Seidov_, Jun 26 2009