OFFSET
1,1
COMMENTS
LINKS
V. Shevelev, Several results on sequences which are similar to the positive integers arXiv:0904.2101 [math.NT], 2009.
MATHEMATICA
a2828[n_] := Which[SquaresR[1, n]>0, 1, SquaresR[2, n]>0, 2, SquaresR[3, n] > 0, 3, True, 4];
a[1] = 4; a[n_] := a[n] = For[k = a[n-1]+1, True, k++, If[a2828[k] == a2828[n], Return[k]]];
Array[a, 63] (* Jean-François Alcover, Jul 28 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Apr 17 2009, May 04 2009
EXTENSIONS
137 replaced by 136, extended by R. J. Mathar, Sep 17 2009
STATUS
approved