OFFSET
1,2
FORMULA
EXAMPLE
a(12) = 1 because its prime factors (2x2x3) have a maximum difference of 1 (3-2).
a(14) = 5 because its prime factors (2x7) have a maximum difference of 5 (7-2).
PROG
(Python)
import numpy as np
def primeFactors(n):
x=[]
while n % 2 == 0:
x.append(2),
n = n / 2
for i in range(3, int(np.sqrt(n))+1, 2):
while n % i== 0:
x.append(i),
n = n / i
if n > 2:
x.append(n)
if len(x)==0:
x.append(1)
if len(x)!=1:
y=x[-1]-x[0]
else:
y=x[0]
return y
print(len(x))
nums = list(range(1, 101))
final=[]
for i in nums:
final.append(primeFactors(i))
final = [int(i) for i in final]
print(final)
(Python)
from sympy import primefactors, isprime
def A335940(n):
if isprime(n):
return n
else:
pf = primefactors(n)
return max(pf)-min(pf) # Chai Wah Wu, Jul 01 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Elam Blackwell, Jun 30 2020
STATUS
approved