A073142 - OEIS

A073142

List of smallest solutions for some k of x = f^k(x), n <> f^j(n) for j < k, where f: m -> |m - reverse(m)|.

%I #5 Mar 30 2012 17:27:38

%S 0,2178,11436678,108811891188,118722683079

%N List of smallest solutions for some k of x = f^k(x), n <> f^j(n) for j < k, where f: m -> |m - reverse(m)|.

%C In the definition, j can be restricted to proper divisors of k. A073143 gives the corresponding values of k. A073144(n) gives the smallest m such that the 'Reverse and Subtract' trajectory of m leads to a(n). Presumably a(6) = 1186781188132188 with k = 17.

%e a(3) = 11436678 is the smallest solution of x = f^14(x) and there is no k such that x = f^k(x) has a smallest solution between a(2) = 2178 and a(3).

%Y Cf. A072137, A072141, A072142, A072143, A072718, A072719, A073143, A073144.

%K base,more,nonn

%O 1,2

%A _Klaus Brockhaus_, Jul 17 2002

%E Offset changed by _N. J. A. Sloane_, Dec 01 2007