A210322 Number of 5-divided binary words of length n.

0, 0, 0, 0, 0, 0, 0, 0, 6, 36, 150, 464, 1304, 3349, 8213, 19230, 43867, 97644, 213776, 461240, 984603, 2082436

Offset

1,9

Comments

See A210109 for further information.

References

Computed by David Scambler, Mar 19 2012

Links

Table of n, a(n) for n=1..22.

Prog

(Python)
from itertools import product, combinations, permutations
def is5div(b):
    for i, j, k, l in combinations(range(1, len(b)), 4):
        divisions = [b[:i], b[i:j], b[j:k], b[k:l], b[l:]]
        all_greater = True
        for p, bp in enumerate(permutations(divisions)):
            if p == 0: continue
            if b >= "".join(bp): all_greater = False; break
        if all_greater: return True
    return False
def a(n): return sum(is5div("".join(b)) for b in product("01", repeat=n))
print([a(n) for n in range(1, 13)]) # Michael S. Branicky, Aug 27 2021

Crossrefs

Cf. A210109, A210321.

Sequence in context: A018214 A181478 A223841 * A056268 A001117 A353664

Adjacent sequences: A210319 A210320 A210321 * A210323 A210324 A210325

Keyword

nonn,more

Author

N. J. A. Sloane, Mar 20 2012

Extensions

a(17)-a(22) from Michael S. Branicky, Aug 27 2021

Status

approved