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
KEYWORD
nonn,base,more
AUTHOR
Meritxell Vila Miñana, Sep 20 2017
EXTENSIONS
Terms ordered by Ray Chandler, Sep 27 2017
STATUS
approved