A100435 Number of distinct products i*j*k for 1 <= i <= j < k <= n.

0, 1, 4, 9, 18, 26, 44, 57, 76, 93, 135, 153, 212, 245, 282, 317, 414, 452, 575, 624, 690, 759, 935, 986, 1103, 1196, 1297, 1378, 1645, 1716, 2024, 2136, 2279, 2427, 2597, 2687, 3110, 3292, 3483, 3606, 4123, 4262, 4837, 5026, 5227, 5485, 6168, 6318, 6725

Offset: 1

Author

N. J. A. Sloane, Nov 21 2004

Keywords

• nonn

Crossrefs

Cf. A027428, A027425, A027430, A100436.

Programs

Maple

f:=proc(n) local i,j,k,t1; t1:={}; for i from 1 to n-1 do for j from i to n-1 do for k from j+1 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, n}, {k, j + 1, n}] ]]]; Table[ f[n], {n, 49}] (* Robert G. Wilson v, Dec 14 2004 *)

Python

def A100435(n): return len({i*j*k for i in range(1,n+1) for j in range(1,i) for k in range(1,j+1)}) # Chai Wah Wu, Oct 16 2023

Extensions

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