OFFSET
0,3
COMMENTS
No term in the sequence is congruent to 3 or 6 (mod 9).
LINKS
Mehmet A. Ates, Table of n, a(n) for n = 0..19599
Mathematical Association of America, 2019 William Lowell Putnam Mathematical Competition Problems
EXAMPLE
For n=3, a(n) = f[1,1,0] = 1^3 + 1^3 + 0^3 - 3*1*1*0 = 2.
MATHEMATICA
SeqSize = 30;
ListSize = 120;
F3List = List[];
f3[a_, b_, c_] := a^3 + b^3 + c^3 - 3*a*b*c
For[i = 0, i <= SeqSize, i++, For[j = 0, j <= i, j++, For[k = 0, k <= j, k++, AppendTo[F3List, f3[i, j, k]]]]]
ListPlot[F3List, PlotLabel -> "a(n)"]
Print["First ", ListSize, " elements of a(n): ", Take[F3List, ListSize]]
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Mehmet A. Ates, Jun 08 2020
EXTENSIONS
Edited by N. J. A. Sloane, Aug 06 2020
STATUS
approved