OFFSET
0,4
COMMENTS
This is very similar to A333307. See that sequence for details about the precise definition. - N. J. A. Sloane, Nov 29 2020
EXAMPLE
a(7) = 0, since:
0 yields a square subsequence of length 2: [0, 0],
1 of length 4: [0, 1, 0, 1],
2 of length 8: [0, 1, 0, 2, 0, 1, 0, 2].
PROG
(Python)
def a333325(n):
seq = []
for k in range(n):
options = []
l = len(seq) + 1
for m in range(3): # base
for i in range(l // 2, -1, -1):
if seq[l - 2 * i: l - i] == seq[l - i:] + [m]: break
options.append(2 * i)
seq.append(options.index(min(options)))
return seq
print(a333325(81))
CROSSREFS
KEYWORD
nonn
AUTHOR
Jan Koornstra, Mar 15 2020
STATUS
approved