A224839 a(1) = 1 and a(n) is the smallest number greater than a(n-1) with no square difference with any preceding term.

1, 3, 6, 8, 11, 13, 16, 18, 21, 23, 35, 40, 45, 53, 58, 63, 66, 68, 73, 86, 96, 110, 120, 125, 128, 131, 133, 138, 143, 148, 151, 171, 178, 181, 183, 188, 193, 198, 205, 211, 216, 239, 244, 250, 256, 258, 261, 263, 268, 273

Offset

1,2

Comments

The first 11 terms are identical to those of A210570.

Links

Jean-François Alcover, Table of n, a(n) for n = 1..1000

Maple

N:= 1000: # to get all terms <= N
V:= Vector(N):
Res:= NULL:
for m from 1 to N do
  if V[m] = 0 then
    V[m]:= 1;
    Res:= Res, m;
    for k from 1 to floor(sqrt(N-m)) do V[m+k^2]:= 1 od:
  fi
od:
Res; # Robert Israel, Nov 30 2016

Mathematica

a[1] = 1; a[n_] := a[n] = For[k = a[n-1]+1, True, k++, If[FreeQ[k - Array[a, n-1], d_ /; IntegerQ[Sqrt[d]]], Return[k]]]; Table[a[n], {n, 1, 40}]

Prog

(Haskell)
a224839 n = a224839_list !! (n-1)
a224839_list = f [1..] [] where
   f (x:xs) ys = if all ((== 0) . a010052) $ map (x -) ys
                    then x : f xs (x:ys) else f xs ys
-- Reinhard Zumkeller, May 02 2014

Crossrefs

Cf. A210570.

Cf. A010052.

Sequence in context: A047219 A139477 A210570 * A122437 A286988 A090848

Adjacent sequences: A224836 A224837 A224838 * A224840 A224841 A224842

Keyword

nonn

Author

Jean-François Alcover, Sep 18 2013

Status

approved