OFFSET
2,1
COMMENTS
In the first 10000 terms the largest value is a(9031) = 1924, with a corresponding power of 2 of approximately 1.52*10^579.
LINKS
Scott R. Shannon, Table of n, a(n) for n = 2..10000
EXAMPLE
a(2) = 2 as 2^2 = 4 written in base 2 = 100_2 which contains adjacent 0's.
a(6) = 6 as 2^6 = 64 written in base 6 = 144_6 which contains adjacent 4's.
a(10) = 16 as 2^16 = 65536 written in base 10 = 65536_10 which contains adjacent 5's.
MAPLE
f:= proc(n) local k, L;
for k from 1 do
L:= convert(2^k, base, n);
if member(0, L[2..-1]-L[1..-2]) then return k fi
od
end proc:
map(f, [$2..100]); # Robert Israel, Jan 09 2024
PROG
(Python)
from itertools import count
from sympy.ntheory.factor_ import digits
def A368866(n):
k = 1
for m in count(1):
k <<= 1
s = digits(k, n)[1:]
if any(s[i]==s[i+1] for i in range(len(s)-1)):
return m # Chai Wah Wu, Jan 08 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Scott R. Shannon, Jan 08 2024
STATUS
approved