OFFSET
0,1
COMMENTS
Also a(n) is the smallest integer that cannot be obtained by using the number 1 at most n+1 times and the operators +, -, *, /. - Koksal Karakus (karakusk(AT)hotmail.com), May 27 2002
LINKS
Juris Cernenoks, Janis Iraids, Martins Opmanis, Rihards Opmanis, and Karlis Podnieks, Integer Complexity: Experimental and Analytical Results II, arxiv:1409.0446 [math.NT], 2014; see Table 2.
EXAMPLE
a(4)=7 because by using the number 1 at most five times we can write 1=1, 1+1=2, 1+1+1=3, 1+1+1+1+1=5, (1+1)*(1+1+1)=6 but we cannot obtain 7 in the same way.
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved