

A295863


Number of ordered pairs of lengthn mutually overlapping binary strings.


1



2, 6, 30, 130, 536, 2174, 8746, 35070, 140438, 562008, 2248460, 8994530, 35979160, 143917970, 575673270, 2302692898, 9210765608
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OFFSET

1,1


COMMENTS

A pair of strings (u,v) is mutually overlapping if some nonempty suffix of u is a prefix of v, and vice versa, such as (00101010,10110001).
All terms are even.  Michael S. Branicky, Dec 06 2020


LINKS

Table of n, a(n) for n=1..17.


PROG

(Python)
from itertools import product
def overlapping(u, v):
for i in range(1, 1+min(len(u), len(v))):
if v[:i]==u[i:]: return True
return False
def a(n):
out = 0
for u in product("01", repeat=n1):
u = ("0", ) + u
for v in product("01", repeat=n):
if overlapping(u, v) and overlapping(v, u): out += 1
return 2*out # by symmetry
print([a(n) for n in range(1, 11)]) # Michael S. Branicky, Dec 06 2020


CROSSREFS

Cf. A296600.
Sequence in context: A065563 A035105 A073969 * A224530 A120950 A055695
Adjacent sequences: A295860 A295861 A295862 * A295864 A295865 A295866


KEYWORD

nonn,more


AUTHOR

Jeffrey Shallit, Feb 13 2018


EXTENSIONS

a(14)a(17) from Michael S. Branicky, Dec 06 2020


STATUS

approved



