A072142 Numbers n such that 14 applications of 'Reverse and Subtract' lead to n, whereas fewer than 14 applications do not lead to n.

11436678, 13973058, 19582398, 23981958, 30581397, 32662377, 33218856, 42464466, 44664246, 48737106, 61936974, 69746193, 71064873, 76226733

Offset: 1

Author

Klaus Brockhaus, Jun 24 2002

Keywords

• base
• nonn

Comments

There are 14 eight-digit terms in the sequence. Further terms are obtained (a) by inserting at the center of these terms either any number of 9's (for 11436678, 32662377, 33218856, 76226733) or any number of 0's (for the other ten terms) and (b) by concatenating a term any number of times with itself and inserting an equal number of 0's at all junctures. Method (b) may be applied recursively to all terms. - Revised thanks to a comment from Hans Havermann, Jan 20 2004.

Examples

			11436678 -> 76226733 -> 42464466 -> 23981958 -> 61936974 -> 13973058 -> 71064873 -> 33218856 -> 32662377 -> 44664246 -> 19582398 -> 69746193 -> 30581397 -> 48737106 -> 11436678.
		

Crossrefs

Cf. A072137, A072140, A072141, A072143, A072718, A072719.

Formula

n = f^14(n), n <> f^k(n) for k < 14, where f: x -> |x - reverse(x)|.