OFFSET
0,1
COMMENTS
FORMULA
EXAMPLE
a(0) = 3 because 3^0 + 3 = 4 = A001358(1) and no semiprime is closer to 3^0.
a(1) = 1 because 3^1 + 1 = 4 = A001358(1) and no semiprime is closer to 3^1.
a(2) = 0 because 3^2 + 0 = 9 = 3^2 = A001358(3), no semiprime is closer to 3^2 [this is the only 0 element].
a(3) = -1 because 3^3 - 1 = 26 = 2 * 13, no semiprime is closer.
a(4) = 1 because 3^4 + 1 = 82 = 2 * 41, no semiprime is closer.
a(5) = 4 because 3^5 + 4 = 247 = 13 * 19, no semiprime is closer.
CROSSREFS
KEYWORD
easy,sign,less
AUTHOR
Jonathan Vos Post, Mar 13 2006
STATUS
approved