The 285th triangular number is also pentagonal and hexagonal. This problem requires us to find the next triangular number that also has this property. This code runs in under half a second on my tablet.

I am running out of easy problems to solve.

```
from math import sqrt
def is_pent(x):
j = (sqrt(24*x + 1) + 1) / 6
if j >= 1:
if j / int(j) == 1: return True
else: return False
def is_hex(x):
j = (sqrt(8*x + 1) + 1) /4
if j >= 1:
if j / int(j) == 1: return True
else: return False
found = False
n = 286
while not found:
t = int(n*(n+1)/2)
if is_pent(t) and is_hex(t):
found = True
print(t)
n = n + 1
```