|
|
A216093
|
|
a(n) = 10^n - (5^(2^n) mod 10^n).
|
|
7
|
|
|
5, 75, 375, 9375, 9375, 109375, 7109375, 87109375, 787109375, 1787109375, 81787109375, 81787109375, 81787109375, 40081787109375, 740081787109375, 3740081787109375, 43740081787109375, 743740081787109375
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
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 5^n and a(n) + 1 is divisible by 2^n. - Eric M. Schmidt, Sep 01 2012
a(n+1) + a(n)^2 == 0 (mod 10^(n+1)). - Robert Israel, Apr 24 2017
|
|
LINKS
|
|
|
FORMULA
|
2^(4*5^(n-1)) mod 10^n - 1.
|
|
MAPLE
|
f:= n -> (-5 &^(2^n) mod 10^n):
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|