OFFSET
1,2
COMMENTS
This is conjectured to be a permutation of the natural numbers.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000
MATHEMATICA
a={1}; While[Length[a]<1000, e=Last@a; s = Select[ Complement[ Range@e, a], SquareFreeQ[e^2 + #^2]&, 1]; If[s!={}, s=s[[1]], s=e+1; While[ MemberQ[a, s] || !SquareFreeQ[ e^2 + s^2], s++]]; AppendTo[a, s]]; a (* first 1000 terms, Giovanni Resta, Jun 02 2015 *)
PROG
(PARI) v=[1]; n=1; while(n<100, if(issquarefree(n^2+v[#v]^2)&&!vecsearch(vecsort(v), n), v=concat(v, n); n=0); n++); v
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Derek Orr, Jun 01 2015
STATUS
approved