A100436 Number of distinct products i*j*k for 1 <= i < j <= k <= n.

0, 1, 4, 10, 20, 27, 46, 61, 84, 101, 147, 163, 226, 256, 292, 331, 434, 472, 601, 655, 719, 785, 968, 1016, 1143, 1233, 1346, 1433, 1713, 1778, 2099, 2219, 2363, 2509, 2677, 2763, 3202, 3381, 3573, 3690, 4223, 4360, 4951, 5149, 5347, 5598, 6298, 6449

Offset: 1

Author

N. J. A. Sloane, Nov 21 2004

Keywords

• nonn

Crossrefs

Cf. A027425, A027430, A100435.

Programs

Maple

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

Mathematica

f[n_] := Length[ Union[ Flatten[ Table[ i*j*k, {i, n}, {j, i + 1, n}, {k, j, n}]]]]; Table[ f[n], {n, 48}] (* Robert G. Wilson v, Dec 14 2004 *)

Python

def A100436(n): return len({i*j*k for i in range(1,n+1) for j in range(1,i+1) for k in range(1,j)}) # Chai Wah Wu, Oct 16 2023

Extensions

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