This site is supported by donations to The OEIS Foundation.

 Annual Appeal: Please make a donation to keep the OEIS running. In 2018 we replaced the server with a faster one, added 20000 new sequences, and reached 7000 citations (often saying "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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

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

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