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 A292634 Numbers n such that 4 iterations of 'Reverse and Subtract' lead to n, whereas fewer than 4 iterations do not lead to n. 9
 169140971830859028, 312535222687464777, 464929563535070436, 651817066348182933 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS There are 4 eighteen-digit terms in the sequence. Terms of derived sequences can be obtained either by inserting at the center of their digits any number of 9's or by concatenating a term any number of times with itself and inserting an equal number of 0's at all junctures. LINKS J. H. E. Cohn, Palindromic differences, Fibonacci Quart. 28 (1990), no. 2, 113-120. FORMULA n = f^4(n), n <> f^k(n) for k < 4, where f: x -> |x - reverse(x)|. EXAMPLE |169140971830859028 - 820958038179041961| = 651817066348182933 |651817066348182933 - 339281843660718156| = 312535222687464777 |312535222687464777 - 777464786222535213| = 464929563535070436 |464929563535070436 - 634070535365929464| = 169140971830859028 CROSSREFS Cf. A072142, A072143, A072718, A072719, A215669, A292635, A292846, A292856, A292857, A292858, A292859. Sequence in context: A317914 A317255 A261152 * A308287 A295740 A270271 Adjacent sequences:  A292631 A292632 A292633 * A292635 A292636 A292637 KEYWORD nonn,base,more AUTHOR Meritxell Vila Miñana, Sep 20 2017 EXTENSIONS Terms ordered by Ray Chandler, Sep 27 2017 STATUS approved

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Last modified January 18 13:49 EST 2020. Contains 331010 sequences. (Running on oeis4.)