OFFSET
0,2
COMMENTS
For any x, one of x+2, x+4, ..., x+18 is divisible by 9 and thus not squarefree, so a(n) does not exist for n >= 9. - Robert Israel, Apr 27 2015
EXAMPLE
a(0) = 1 because 1 + 0 = 1 is squarefree.
a(1) = 3 because 3 + 1 = 4 is not squarefree and 3 + 2 = 5 is squarefree.
PROG
(PARI) a(n)=k=1; while(k, c=0; for(i=1, n, if(!issquarefree(k+2*i-1)&&issquarefree(k+2*i), c++); if(issquarefree(k+2*i-1)||!issquarefree(k+2*i), c=0; break)); if(c==n, return(k)); k++)
vector(9, n, n--; a(n)) \\ Derek Orr, Apr 27 2015
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
Juri-Stepan Gerasimov, Apr 25 2015
EXTENSIONS
Corrected and extended by Derek Orr, Apr 27 2015
STATUS
approved