OFFSET
0,2
COMMENTS
At each step you are allowed to either double x -> 2*x or double and reverse x -> R(2*x), where R(x) = A004086(x) is decimal digit reversal.
LINKS
Michael S. Branicky, Table of n, a(n) for n = 0..34
FORMULA
a(n) <= 20^n and a(n+1) <= 20*a(n).
EXAMPLE
a(4) = 61 by the path 1, 2, 4, 8, 61.
PROG
(Python)
from itertools import islice
def reverse(n): return int(str(n)[::-1])
def agen(): # generator of terms
reach = {1}
while True:
yield max(reach)
newreach = set()
for q in reach: newreach.update([2*q, reverse(2*q)])
reach = newreach
print(list(islice(agen(), 28))) # Michael S. Branicky, Apr 14 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Bryle Morga and Michael S. Branicky, Apr 14 2024
STATUS
approved