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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A146025 Numbers that can be written from base 2 to base 5 using only the digits 0 and 1. 9
0, 1, 82000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Conjectured to be complete. a(4), if it exists, is greater than 10^15. - Charles R Greathouse IV, Apr 06 2012

Checked to 3125 (5^5) base-5 digits in just under 1/2 hour using a minor modification of the PARI program at A230360.  Interestingly, with 5 replaced by 9 and the digits 2 and 3 permitted, it appears the complete set is--somewhat coincidental with this--{0, 1, 2, 3, 8281, 8282, 8283}. - James G. Merickel, Dec 01 2013

Checked to 11 million decimal digits in 1 week using an algorithm that, upon finding that the current guess has non-{0,1} digits in a particular base, increases the guess to only have {0,1} digits in that base. C code in links. - Alex P. Klinkhamer, Aug 29 2015

LINKS

Table of n, a(n) for n=1..3.

James Grime and Brady Haran, Why 82,000 is an extraordinary number - Numberphile (2015)

Alex P. Klinkhamer, search82000.c code on GitHub.

EXAMPLE

82000 = 10100000001010000 (2) = 11011111001 (3) = 110001100 (4) = 10111000 (5).

MATHEMATICA

f[n_] := Total[Total@ Drop[RotateRight[DigitCount[n, #]], 2] & /@ Range[3, 5]]; Select[Range[0, 100000], f@ # == 0 &] (* Michael De Vlieger, Aug 29 2015 *)

PROG

(PARI) is(n)=vecmax(digits(n, 5))<2 && vecmax(digits(n, 4))<2 && vecmax(digits(n, 3))<2 \\ Charles R Greathouse IV, Aug 31 2015

CROSSREFS

Intersection of A005836, A000695, and A033042.

Cf. A131646, A146027, A230360, A258107.

Sequence in context: A134122 A138044 A098187 * A253957 A253964 A253760

Adjacent sequences:  A146022 A146023 A146024 * A146026 A146027 A146028

KEYWORD

bref,fini,full,nonn,base,changed

AUTHOR

Daniel Mondot (dmondot(AT)gmail.com), Oct 26 2008

EXTENSIONS

Edited by Charles R Greathouse IV, Nov 01 2009

Search limit extended to astronomical odds by James G. Merickel, Dec 03 2013

Search limit increased again with example code by Alex P. Klinkhamer, Aug 29 2015

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified September 3 11:24 EDT 2015. Contains 261316 sequences.