

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




OFFSET

1,1


COMMENTS

There are 4 eighteendigit 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, 113120.


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



