A100439 Number of distinct values of i*j + j*k + k*i with 1 <= i<j<k <= n.

0, 0, 1, 4, 10, 20, 31, 48, 70, 96, 123, 161, 197, 240, 293, 340, 394, 460, 524, 596, 670, 744, 819, 918, 1016, 1112, 1217, 1322, 1429, 1561, 1679, 1798, 1943, 2072, 2218, 2379, 2518, 2669, 2838, 3009, 3178, 3361, 3536, 3713, 3924, 4120, 4304, 4522, 4727

Offset

1,4

Links

Table of n, a(n) for n=1..49.

Maple

f:=proc(n) local i, j, k, t1; t1:={}; for i from 1 to n-2 do for j from i+1 to n-1 do for k from j+1 to n do t1:={op(t1), i*j+j*k+k*i}; od: od: od: t1:=convert(t1, list); nops(t1); end;

Mathematica

f[n_] := Length[ Union[ Flatten[ Table[i*j + j*k + k*i, {i, n}, {j, i + 1, n}, {k, j + 1, n}] ]]]; Table[ f[n], {n, 49}] (* Robert G. Wilson v, Dec 14 2004 *)

Crossrefs

Cf. A027430, A100440, A102533, A102534.

Sequence in context: A100436 A348011 A009882 * A301193 A301180 A357837

Adjacent sequences: A100436 A100437 A100438 * A100440 A100441 A100442

Keyword

nonn

Author

N. J. A. Sloane, Nov 21 2004

Extensions

More terms from Robert G. Wilson v, Dec 14 2004

Status

approved