[seqfan] Re: correcting A181539
RGWv
rgwv at rgwv.com
Thu Nov 4 07:02:41 CET 2010
?%I A181539
%S A181539
1,51,751,8751,18751,218751,4218751,74218751,574218751,3574218751,
! %T A181539
63574218751,163574218751,163574218751,80163574218751,480163574218751,
! %U A181539
7480163574218751,87480163574218751,487480163574218751,5487480163574218751
! %N A181539 a(n) = m, an n digit number (leading zero suspended when
appropriate) such that m^2 == 1 mod 10^n and a(n-1) is a substring.
%e A181539 For n = 4; 8751^2 = 76580001 == 1 mod 10^4.
! %H A181539 Robert G. Wilson v, <a href="b181539.txt"> Table of n,
a(n) for n = 1..150 </a>.
! %K A181539 base,nonn,new
%O A181539 1,2
+ %Y A181539 Cf. A007185, A016090, A181628.
%A A181539 Kevin Batista (kevin762401(AT)yahoo.com), Oct 29 2010
%E A181539 Edited by N. J. A. Sloane, Oct 29 2010
+ %E A181539 Edited and extended by Robert G. Wilson v, (rgwv(AT)rgwv.com)
Nov 02 2010
-----Original Message-----
From: N. J. A. Sloane
Sent: Wednesday, November 03, 2010 10:44 AM
To: seqfan at list.seqfan.eu
Cc: njas at research.att.com ; rgwv at rgwv.com
Subject: Re: [seqfan] Re: correcting A181539
Bob Wilson wrote to me about this sequence,
pointing out that it did not
match the definition, and offering to edit it.
Bob, what did you come up with?
Neil
>The current A181539 does not seem to match its definition:
>for example, why a(2)=51 and not a(2)=49 (let alone a(2)=1)?
>I would rather change the definition to:
>a(n) = smallest number m > 1 such that m^2 == 1 (mod 10^n)
>that would give a sequence:
>9, 49, 249, 1249, 18751, 218751, 781249, 24218751, 74218751,
>1425781249, 13574218751, 163574218751, 163574218751, 19836425781249,
>19836425781249, 2480163574218751, 12519836425781249,
>12519836425781249, 487480163574218751, 15487480163574218751,
>215487480163574218751, 215487480163574218751, 4784512519836425781249,
>45215487480163574218751, 45215487480163574218751
>Regards,
>Max
>On Wed, Nov 3, 2010 at 8:29 AM, Richard Mathar
><mathar at strw.leidenuniv.nl> wrote:
>>
>> Is there a way to keep the terms in http://oeis.org/classic/A181539
>> (current definition m: m^2 =1 (mod 10^n) by changing the definition? I'd
>> expect
>> some corresponding terms of http://oeis.org/classic/A181607 Â to appear,
>> but I
>> cannot figure out which modification in A181539 would do that
>> selection/matching.
>>
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