OFFSET
1,2
COMMENTS
20^20-11111111111111111111=104857588888888888888888889 is the only known prime term of this sequence. Next such prime has more than 40000 digits (n>10000)!
LINKS
Robert Israel, Table of n, a(n) for n = 1..386
FORMULA
a(n) = n^n - (10^n-1)/9. - Robert Israel, Oct 23 2016
EXAMPLE
a(2) = 2^2-11 = -7, a(8) = 8^8-11111111 = 5666105.
MAPLE
seq(n^n - (10^n-1)/9. n=1..20); # Robert Israel, Oct 23 2016
MATHEMATICA
Table[n^n - (10^n - 1)/9, {n, 17}]
CROSSREFS
KEYWORD
easy,sign,base
AUTHOR
Ali Heydarian (mymontain(AT)yahoo.com), May 13 2010
STATUS
approved