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Least number that requires n steps to reach 0 by repeated application of f: x -> abs(x - reverse(x)).
0

%I #4 Dec 05 2013 19:57:00

%S 0,1,10,16,14,15,13,1011,1017,1037,1027,1014,1013,1028,100143,100135,

%T 100145,100134,100103,100195,100137,100227,100114,100128,100194,

%U 100107,100307,100277,100413,100345,100429,100215,100444,100237,100433,100335

%N Least number that requires n steps to reach 0 by repeated application of f: x -> abs(x - reverse(x)).

%C Coincides with A072138 for the first 14 and many later terms.

%e f(16) = 61-16 = 45, f(45) = 54-45 = 9, f(9) = 9-9 = 0. For no k < 16 exactly three steps lead to 0, hence a(3) = 16.

%Y Cf. A072137, A072138, A072141.

%K base,nonn

%O 0,3

%A _Amarnath Murthy_, Jul 13 2005

%E Edited, corrected and extended by _Klaus Brockhaus_, Jul 14 2005