Triangle, pentagonal, and hexagonal numbers are generated by the following formulae:
Triangle Tn=n(n+1)/2 1, 3, 6, 10, 15, …
Pentagonal Pn=n(3n−1)/2 1, 5, 12, 22, 35, …
Hexagonal Hn=n(2n−1) 1, 6, 15, 28, 45, …
It can be verified that T285 = P165 = H143 = 40755.
Find the next triangle number that is also pentagonal and hexagonal.
import math
def T(n):
return (math.sqrt(8 * n + 1) - 1) % 2 == 0
def P(n):
return (math.sqrt(24 * n + 1) + 1) % 6 == 0
def H(n):
return (math.sqrt(8 * n + 1) + 1) % 4 == 0
i = 144
while True:
h = i * (2 * i - 1)
if T(h) and P(h):
print h
break
i += 1
做完44,这题一点儿难度都木有