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A292856
Numbers n such that 7 applications of 'Reverse and Subtract' lead to n, whereas fewer than 7 applications do not lead to n.
10
142710354353443018141857289645646556981858, 236547461211163745741763452538788836254258, 331948602685207939133668051397314792060866, 336111694728585211732663888305271414788267
OFFSET
1,1
COMMENTS
There are 7 forty-two-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^7(n), n <> f^k(n) for k < 7, where f: x -> |x - reverse(x)|.
EXAMPLE
142710354353443018141857289645646556981858 -> 715479301293103964616284520698706896035383 -> 331948602685207939133668051397314792060866 -> 336111694728585211732663888305271414788267 -> 426775719443918676633573224280556081323366 -> 236547461211163745741763452538788836254258 -> 615905177676671508625384094822323328491374 -> 142710354353443018141857289645646556981858
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
Terms ordered by Ray Chandler, Sep 27 2017
STATUS
approved