|
|
A071694
|
|
Number of ways to write n as n = x*y*z/(x+y+z) 1 <= x <= y <= z <= n.
|
|
1
|
|
|
0, 0, 1, 0, 1, 0, 1, 2, 2, 1, 2, 3, 1, 3, 5, 3, 2, 3, 2, 7, 5, 1, 3, 8, 2, 4, 8, 4, 3, 5, 2, 9, 5, 2, 14, 12, 1, 4, 10, 10, 3, 5, 2, 11, 11, 2, 4, 13, 5, 10, 8, 6, 3, 14, 12, 22, 5, 1, 5, 14, 1, 5, 22, 11, 13, 11, 2, 11, 9, 6, 5, 19, 1, 5, 19, 10, 13, 6, 4, 33, 14, 1, 5, 24, 6, 6, 11, 10, 5
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,8
|
|
COMMENTS
|
|
|
LINKS
|
|
|
MAPLE
|
f:= proc(n) local x, y, z, t;
t:= 0;
for x from 1 to n do
for y from max(x, ceil(n/x)) to n do
if x*y = n then next fi;
z:= n*(x+y)/(x*y-n);
if z::integer and z>=y and z<=n then t:= t+1 fi
od od:
t
end proc:
|
|
MATHEMATICA
|
a[n_] := Sum[Boole[x y z/(x + y + z) == n], {x, n}, {y, x}, {z, y}];
|
|
PROG
|
(PARI) for(n=1, 90, print1(sum(a=1, n, sum(b=1, a, sum(c=1, b, if(a*b*c/(a+b+c)-n, 0, 1)))), ", "))
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|