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A292992
Numbers n such that 13 applications of 'Reverse and Subtract' lead to n, whereas fewer than 13 applications do not lead to n.
3
1195005230033599502088049947699664004979, 1381092199992389193086189078000076108069, 1417996648846699605185820033511533003948, 2845548027720844548271544519722791554517
OFFSET
1,1
COMMENTS
There are 13 forty-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^13(n), n <> f^k(n) for k < 13, where f: x -> |x - reverse(x)|.
EXAMPLE
1195005230033599502088049947699664004979 -> 8598999439933899906714010005600661000932 -> 6208997779868899802537910022201311001974 -> 1417996648846699605185820033511533003948 -> 7075006702306600680629249932976933993193 -> 3161013305514201251368389866944857987486 -> 3686884278982488587263131157210175114127 -> 3527231431145022726364727685688549772736 -> 2845548027720844548271544519722791554517 -> 4309003944558309903456909960554416900965 -> 1381092199992389193086189078000076108069 -> 8226924500016320623717730754999836793762 -> 5552948110021750246544470518899782497534 ->
1195005230033599502088049947699664004979.
KEYWORD
nonn,base
AUTHOR
Ray Chandler, Sep 28 2017
STATUS
approved