OFFSET
1,2
COMMENTS
Conjectured to be a permutation of the natural numbers. - Derek Orr, Jun 01 2015
LINKS
Scott R. Shannon, Table of n, a(n) for n = 1..10000
EXAMPLE
9,10,11,12,... are the positive integers not occurring among the first 8 terms of the sequence. a(8) + 9 = 16, which is not squarefree. a(8) + 10 = 17, which is squarefree. So a(9) = 10.
MATHEMATICA
f[s_] := Block[{k = 1}, While[MemberQ[s, k] || Max @@ Last /@ FactorInteger[(s[[ -1]] + k)] > 1, k++ ]; Append[s, k]]; Nest[f, {1}, 75] (* Ray Chandler, Sep 06 2006 *)
PROG
(PARI) v=[1]; n=1; while(n<100, if(issquarefree(v[#v]+n)&&!vecsearch(vecsort(v), n), v=concat(v, n); n=0); n++); v \\ Derek Orr, Jun 01 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Aug 31 2006
EXTENSIONS
Extended by Ray Chandler, Sep 06 2006
STATUS
approved