The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A044251 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A044251

Numbers n such that string 0,0 occurs in the base 9 representation of n but not of n-1.
(history; published version)

#15 by Giovanni Resta at Fri Apr 11 03:46:53 EDT 2014

STATUS

editing

approved

#14 by Giovanni Resta at Fri Apr 11 03:46:45 EDT 2014

COMMENTS

The sequence lists the amount of numbers of n digits with n-1 identical digits. - Paolo P. Lava, Apr 11 2014

FORMULA

a(n) = 81*n [Paolo P. Lava, Apr 11 2014]

STATUS

proposed

editing

#13 by Paolo P. Lava at Fri Apr 11 03:34:45 EDT 2014

STATUS

editing

proposed

Discussion

Fri Apr 11

03:41

Giovanni Resta: The formula and the comment are both wrong. As observed by Wilson, 6642 = (10100)_9 is a multiple of 81 but it is not in the sequence because 6642-1 = (10088)_9. And  6642=(10100) has not n-1 identical digits.

03:46

Giovanni Resta: I did not read correctly the comment, so the second part of my previous pink box does not make sense. But now that I understand it, it is false anyway, because of the fact that 81*n is not the formula (because some multiples of 81 are missing in the sequence) makes the comment wrong anyway. I will revert to original.

#12 by Paolo P. Lava at Fri Apr 11 03:09:41 EDT 2014

COMMENTS

The sequence lists the amount of numbers of n digits with n-1 identical digits. - Paolo P. Lava, Apr 11 2014

FORMULA

a(n) = 81*n [Paolo P. Lava, Apr 11 2014]

STATUS

approved

editing

#11 by Russ Cox at Fri Mar 30 18:56:43 EDT 2012

AUTHOR

Clark Kimberling (ck6(AT)evansville.edu)

Clark Kimberling

Discussion

Fri Mar 30

18:56

OEIS Server: https://oeis.org/edit/global/285

#10 by Russ Cox at Fri Mar 30 18:35:35 EDT 2012

COMMENTS

Every element is a multiple of 81. The smallest positive multiple of 81 not in the sequence is 6642. - _David W. Wilson (davidwwilson(AT)comcast.net), _, Aug 03 2005

Discussion

Fri Mar 30

18:35

OEIS Server: https://oeis.org/edit/global/202

#9 by N. J. A. Sloane at Sat Nov 10 03:00:00 EST 2007

COMMENTS

Every element is a multiple of 81. The smallest positive multiple of 81 not in the sequence is 6642. - David W. Wilson (davidwwilson(AT)comcast.net), Aug 03 2005

KEYWORD

nonn,base,new

#8 by N. J. A. Sloane at Fri May 11 03:00:00 EDT 2007

LINKS

Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/NonRecursions.html">Non Recursions</a>

KEYWORD

nonn,base,new

#7 by N. J. A. Sloane at Fri Sep 29 03:00:00 EDT 2006

COMMENTS

Every element is a multiple of 81. The smallest positive multiple of 81 not in the seqence sequence is 6642. - David Wilson (davidwwilson(AT)comcast.net), Aug 03 2005

KEYWORD

nonn,base,new

#6 by N. J. A. Sloane at Wed Sep 21 03:00:00 EDT 2005

COMMENTS

Every element is a multiple of 81. The smallest positive multiple of 81 not in the seqence is 6642. - David Wilson (davidwwilson(AT)comcast.net), Aug 03 2005

FORMULA

a(n) = 81*n (conjectured) (from Mitch Harris, Jun 29 2005)

KEYWORD

nonn,base,new