OFFSET
0,3
COMMENTS
'Recamán transform' (see A005132) of the squares.
LINKS
Samuel Harkness, Table of n, a(n) for n = 0..10000
Nick Hobson, Python program for this sequence
MATHEMATICA
a = {0, 1}; Do[If[a[[-1]] - n^2 >= 0 && Position[a, a[[-1]] - n^2] == {}, a = Append[a, a[[-1]] - n^2], a = Append[a, a[[-1]] + n^2]], {n, 2, 49}]; Print[a] (* Samuel Harkness, Sep 20 2022 *)
PROG
(PARI) lista(nn) = {my(va = vector(nn)); va[1] = 1; my(sa = Set(va)); for (n=2, nn, my(x = va[n-1] - n^2); if ((x>0) && !setsearch(sa, x), va[n] = x, va[n] = va[n-1] + n^2); sa = Set(va); ); concat(0, va); } \\ Michel Marcus, Sep 26 2022
CROSSREFS
KEYWORD
nonn,hear
AUTHOR
N. J. A. Sloane, Feb 09 2002
STATUS
approved