OFFSET
0,1
LINKS
J. Millar, N. J. A. Sloane and N. E. Young, A new operation on sequences: the Boustrophedon transform, J.Combin. Theory, 17A (1996) 44-54 (Abstract, pdf, ps).
N. J. A. Sloane, Transforms
FORMULA
a(n) appears to be asymptotic to C*n!*(2/Pi)^n where C = 9.27921365277635263761227970562207183019110298580498662908878310... - Benoit Cloitre and Mark Hudson (mrmarkhudson(AT)hotmail.com)
EXAMPLE
We simply apply the Boustrophedon transform to [2,1,2,1,1,4,1,1,6,1,1,8,1,1,...]
PROG
(Python)
from itertools import count, islice, accumulate
def A080408_gen(): # generator of terms
blist = tuple()
for n in count(1):
yield (blist := tuple(accumulate(reversed(blist), initial=2 if n == 1 else 1 if n % 3 else n//3<<1)))[-1]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mark Hudson (mrmarkhudson(AT)hotmail.com), Feb 17 2003
STATUS
approved