A071808 - OEIS

%I #7 Mar 30 2012 18:39:03

%S 1,1,2,10,10,10,10,18,18,18,18,18,18,18,18,126,126,126,126,126,126,

%T 126,126,270,270,270,270,270,270,270,270,270,270,270,270,270,270,270,

%U 270,270,270,270,270,1470,1470,1470,1890,1890,1890,2310,2310,2310,2310

%N Smallest s such that sk+1 is squarefree for 1 <= k <= n.

%C a(n)+1 or a(n)-1 is prime for listed terms.

%o (PARI) for(n=1,57,s=1; while(sum(i=1,n,issquarefree(s*i+1))<n,s++); print1(s,","))

%K easy,nonn

%O 1,3

%A _Benoit Cloitre_, Jun 06 2002