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A332616
a(n) = value of the cubic form A^3 + B^3 + C^3 - 3ABC evaluated at row n of the table in A331195.
1
0, 1, 2, 0, 8, 9, 4, 16, 5, 0, 27, 28, 20, 35, 18, 7, 54, 28, 8, 0, 64, 65, 54, 72, 49, 32, 91, 56, 27, 10, 128, 81, 40, 11, 0, 125, 126, 112, 133, 104, 81, 152, 108, 70, 44, 189, 130, 77, 36, 13, 250, 176, 108, 52, 14, 0, 216, 217, 200, 224, 189, 160, 243
OFFSET
0,3
COMMENTS
No term in the sequence is congruent to 3 or 6 (mod 9).
LINKS
FORMULA
a(n) = A056556(n)^3 + A056557(n)^3 + A056558(n)^3 - 3*A056556(n)*A056557(n)*A056558(n).
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
Cf. A074232 (in ascending order, strictly positive & without duplicates).
Sequence in context: A287542 A288197 A181592 * A097348 A271034 A185965
KEYWORD
nonn,look
AUTHOR
Mehmet A. Ates, Jun 08 2020
EXTENSIONS
Edited by N. J. A. Sloane, Aug 06 2020
STATUS
approved