login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A210326 Number of 5-divided words of length n over a 3-letter alphabet. 3
0, 0, 0, 0, 0, 0, 15, 166, 1135, 5865, 26170, 105224, 396082, 1419981, 4916112 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

See A210109 for further information.

Row sums of the following table which shows how many words of length n over a 3-letter alphabet are 5-divided in k>=1 different ways:

15;

103,43,20;

546,236,162,84,28,51,16,8,5;

2118,1211,848,480,...

- R. J. Mathar, Mar 25 2012

REFERENCES

Computed by David Scambler, Mar 19 2012

LINKS

Table of n, a(n) for n=1..15.

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("012", repeat=n))

print([a(n) for n in range(1, 10)]) # Michael S. Branicky, Aug 28 2021

CROSSREFS

Cf. A210109, A210324, A210325.

Sequence in context: A229406 A118093 A167615 * A016234 A160197 A055660

Adjacent sequences:  A210323 A210324 A210325 * A210327 A210328 A210329

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Mar 20 2012

EXTENSIONS

a(14)-a(15) from Michael S. Branicky, Aug 28 2021

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 17 17:52 EDT 2022. Contains 353778 sequences. (Running on oeis4.)