A292857 Numbers k such that 8 applications of 'Reverse and Subtract' lead to k, whereas fewer than 8 applications do not lead to k.

16914079504181797053273763831171860502859028, 16914099886383117186009041817970531210859028, 31253512653248719266062943707325665377464777, 31253591994370732566027032487192660079464777

Offset: 1

Author

Meritxell Vila Miñana, Sep 25 2017

Keywords

• nonn
• base

Comments

There are 8 forty-four-digit terms in the sequence. Further terms are obtained (a) by inserting at the center of these terms either any number of 0's (for 16914079504181797053273763831171860502859028, 46492964703403651468863122584458570244070436, 65181741002635316783463471248546280094182933) or any number of 9's (for the other five 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. - Clarified by Ray Chandler, Oct 14 2017.

Examples

			16914079504181797053273763831171860502859028 -> 65181741002635316783463471248546280094182933 -> 31253591994370732566027032487192660079464777 -> 46492905012258445857045034036514689840070436 -> 16914099886383117186009041817970531210859028 -> 65181701327124854628081026353167837688182933 -> 31253512653248719266062943707325665377464777 -> 46492964703403651468863122584458570244070436 -> 16914079504181797053273763831171860502859028
		

Links

• Ray Chandler, Table of n, a(n) for n = 1..8
• J. H. E. Cohn, Palindromic differences, Fibonacci Quart. 28 (1990), no. 2, 113-120.

Crossrefs

Cf. A072142, A072143, A072718, A072719, A215669, A292634, A292635, A292846, A292856, A292858, A292859.

Formula

n = f^8(n), n <> f^k(n) for k < 8, where f: x -> |x - reverse(x)|.

Extensions

Terms ordered by Ray Chandler, Sep 27 2017