login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A270029 a(n) is the smallest b for which the base-b representation of n contains at least one 3 (or 0 if no such base exists). 11
0, 0, 4, 0, 0, 0, 4, 5, 6, 7, 4, 4, 4, 4, 4, 5, 5, 5, 4, 6, 6, 6, 4, 7, 7, 7, 4, 4, 4, 4, 4, 9, 5, 9, 4, 10, 10, 5, 4, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 17, 5, 5, 4, 5, 5, 7, 4, 7, 5, 7, 4, 4, 4, 4, 4, 5, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 4, 4, 4, 4, 4, 5, 5, 5, 4, 26 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(n) > 0 for n >= 7 since 13 is n written in base n-3.

The only perfect k-th powers (k >= 2) that can appear in this sequence are 2^k and 3^k with k a prime number.

LINKS

Nathan Fox, Table of n, a(n) for n = 1..10000

MATHEMATICA

Table[SelectFirst[Range[4, 10^3], DigitCount[n, #, 3] > 0 &], {n, 7, 120}] (* Michael De Vlieger, Mar 10 2016, Version 10 *)

PROG

(PARI) a(n) = if ((n<7) && (n!=3), 0, my(b=4); while(!vecsearch(Set(digits(n, b)), 3), b++); b); \\ Michel Marcus, Mar 10 2016

CROSSREFS

Cf. A270027, A270028, A216194, A270030, A270031, A270032, A270033, A270034, A270035, A270039.

Sequence in context: A255263 A153011 A173532 * A028598 A272618 A265397

Adjacent sequences:  A270026 A270027 A270028 * A270030 A270031 A270032

KEYWORD

nonn,base

AUTHOR

Nathan Fox, Mar 08 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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 16 04:26 EDT 2019. Contains 325064 sequences. (Running on oeis4.)