A292992 Numbers n such that 13 applications of 'Reverse and Subtract' lead to n, whereas fewer than 13 applications do not lead to n.

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

Ray Chandler, Table of n, a(n) for n = 1..13

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.

Crossrefs

Cf. A072142, A072143, A072718, A072719, A215669, A292634, A292635, A292846, A292856, A292857, A292858, A292859, A292993.

Sequence in context: A336775 A095472 A105300 * A008870 A008869 A095474

Adjacent sequences: A292989 A292990 A292991 * A292993 A292994 A292995

Keyword

nonn,base

Author

Ray Chandler, Sep 28 2017

Status

approved