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A224839
a(1) = 1 and a(n) is the smallest number greater than a(n-1) with no square difference with any preceding term.
2
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
KEYWORD
nonn
AUTHOR
STATUS
approved