OFFSET
1,1
COMMENTS
a(n)^3 mod 10^n = a(n).
a(n) is the unique positive integer less than 10^n such that a(n) is divisible by 2^n and a(n) + 1 is divisible by 5^n. - Eric M. Schmidt, Sep 01 2012
FORMULA
a(n) = 5^(2^n) mod 10^n - 1.
MATHEMATICA
Table[PowerMod[5, 2^n, 10^n], {n, 20}]-1 (* Harvey P. Dale, Dec 17 2017 *)
PROG
(Sage) def A216092(n) : return crt(0, -1, 2^n, 5^n) # Eric M. Schmidt, Sep 01 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
V. Raman, Sep 01 2012
STATUS
approved