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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

Table of n, a(n) for n=1..4.

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.)