OFFSET
1,1
COMMENTS
The trivial solution is x = 1.
REFERENCES
J. A. H. Hunter, Fun with Figures, Oxford University Press, 1956.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..100
GĂ©rard P. Michon, A decadic puzzle by J.A.H. Hunter (1902-1986)
Greg Ross, Futility Closet Math Note 93
Brent Yorgey, Math Less Traveled: A curiosity
MATHEMATICA
f[n_] := Module[{d}, digs = {7}; Do[d = Select[Range[0, 9], Module[{t}, t = digs~Prepend~#; FromDigits[t] == Mod[2 FromDigits[t]^2 - 1, 10^(Length[digs] + 1)]] &][[1]]; digs = digs~Prepend~d, {n}]; FromDigits[digs]]; Table[f[n - 1], {n, 10}] (* Brenton Bostick, Mar 27 2012 *)
PROG
(PARI) a(n)=lift(chinese(Mod(1, 2^n), Mod(5^n\2, 5^n))) \\ Charles R Greathouse IV, Mar 28 2012
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Michael Brundage, Mar 27 2012
STATUS
approved