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A137850 a(n) = n base 5, under morphism f(1) = 121, f(2) = 123, f(3) = 141, f(4) = 142, or 0 if n base 5 has a zero. 0
121, 123, 141, 142, 0, 121121, 121123, 121141, 121142, 0, 123121, 123123, 123141, 123142, 0, 141121, 141123, 141141, 141142, 0, 142121, 142123, 142141, 142142, 0, 0, 0, 0, 0, 0, 121121121, 121121123, 121121141, 121121142, 0, 121123121, 121123123, 121123141 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..38.

James Currie, Narad Rampersad, Dejean's conjecture holds for n >= 30, arXiv:0806.0044 [math.NT], May 30 2008.

FORMULA

a(n) = A007091(n) under the morphism f(1) = 121, f(2) = 123, f(3) = 141, f(4) = 142, or 0 if n base 5 is not a word in the alphabet {1,2,3,4}* i.e., has a zero.

MATHEMATICA

a[n_] := Block[{d = IntegerDigits[n, 5]}, If[Min[d] == 0, 0, FromDigits[ Flatten[d /. {1 -> {1, 2, 1}, 2 -> {1, 2, 3}, 3 -> {1, 4, 1}, 4 -> {1, 4, 2}}]]]]; Array[a, 38] (* Giovanni Resta, Jun 20 2016 *)

CROSSREFS

Cf. A007091.

Sequence in context: A014734 A137517 A014735 * A262517 A036231 A055468

Adjacent sequences:  A137847 A137848 A137849 * A137851 A137852 A137853

KEYWORD

base,easy,nonn

AUTHOR

Jonathan Vos Post, Jun 03 2008

EXTENSIONS

Data corrected by Giovanni Resta, Jun 20 2016

STATUS

approved

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Last modified December 14 18:21 EST 2018. Contains 318106 sequences. (Running on oeis4.)