A131754 Size of the largest subset of {1,2,...,n} such that no two distinct elements differ by a perfect square > 1.

1, 2, 3, 4, 4, 4, 4, 4, 5, 5, 6, 6, 6, 7, 8, 8, 8, 8, 8, 8, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 12, 13, 13, 13, 13, 13, 14, 15, 15, 15, 15, 15, 15, 16, 17, 17, 17, 17, 17, 17, 18, 19, 19, 19, 19, 19, 19, 20, 20, 20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 21, 22, 23, 24, 24, 24, 24, 24

Offset: 1

Author

Olivier Gérard, Sep 17 2007

Keywords

• nonn

Links

• Fausto A. C. Cariboni, Table of n, a(n) for n = 1..270 (terms n = 1..165 from Robert Israel)
• Fausto A. C. Cariboni, Sets of maximal span that yield a(n) for n = 2..270, Nov 18 2018.

Crossrefs

Cf. A100719, A131752, A131753.

Programs

Maple

f:= proc(n) uses GraphTheory; IndependenceNumber(Graph(n,
   {seq(seq({i,i+x^2},x=2..floor(sqrt(n-i))),i=1..n)}));
end proc:
map(f, [$1..58]); # Robert Israel, Mar 20 2017

Extensions

More terms from Robert Israel, Mar 20 2017