OFFSET
1,1
COMMENTS
Least number m such that m is not a multiple of 10 and m^n is a term of A171901.
a(n) >= 2 and a(n) exists for all n > 0, since for sufficiently large k, floor(10^(k/n))^n = 99.... and has 2 adjacent digits 9.
Conjecture: a(n) = 2 for n > 126, i.e., 2^n has two or more identical adjacent decimal digits for n > 126.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000
EXAMPLE
a(4) = 16 since 16^4 = 65535 has a double digit 5, where i^4 does not have a double digit for i < 16.
PROG
(Python)
def A324309(n):
m, k = 2, 2**n
while True:
s = str(k)
for i in range(1, len(s)):
if s[i] == s[i-1]:
return m
m += 1
if m % 10 == 0:
m += 1
k = m**n
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Chai Wah Wu, Feb 21 2019
STATUS
approved