

A082215


Numbers obtained in the concatenation of terms starting with the first term of A018238.


2



1, 121, 1213121, 121312141213121, 1213121412131215121312141213121, 121312141213121512131214121312161213121412131215121312141213121, 1213121412131215121312141213121612131214121312151213121412131217121312141213121512131214121312161213121412131215121312141213121
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OFFSET

1,2


COMMENTS

Also called Zimin words.
a(n) is a palindrome for n<10; it is debatable whether a(n) can be called a Zimin word for n>=10 (see the Comments in A018238).  Danny Rorabaugh, Sep 26 2015


LINKS

Table of n, a(n) for n=1..7.
J. Cooper and D. Rorabaugh, Bounds on Zimin Word Avoidance, arXiv:1409.3080 [math.CO]; Congressus Numerantium, 222 (2014), 8795.
L. J. Cummings and M. Mays, A onesided Zimin construction, Electron. J. Combin. 8 (2001), #R27.
A. I. Zimin, Blocking sets of terms, Math. USSR Sbornik, 47 (1984), No. 2, 353364.


FORMULA

The Zimin words are defined here by Z_1 = 1, Z_n = Z_{n1}nZ_{n1}.  Dmitry Kamenetsky, Sep 30 2006


MATHEMATICA

a = {1}; Do[w = IntegerDigits@ a[[n  1]]; AppendTo[a, FromDigits@ Join[w, IntegerDigits@ n, w]], {n, 2, 7}]; a (* Michael De Vlieger, Sep 26 2015 *)


CROSSREFS

Cf. A018238, A123121.
See A001511 for another representation of this sequence of digits.
Sequence in context: A317956 A136094 A317197 * A123179 A245593 A053885
Adjacent sequences: A082212 A082213 A082214 * A082216 A082217 A082218


KEYWORD

base,nonn


AUTHOR

Amarnath Murthy, Apr 08 2003


EXTENSIONS

More terms from Joshua Zucker, May 08 2006
"Palindromes" replaced with "Numbers" in sequence name by Danny Rorabaugh, Sep 26 2015


STATUS

approved



