<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-2">
<META content="MSHTML 6.00.2900.2180" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>Hello Seqfans,</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>It's my first post here so let me introduce
myself:<BR>English is not my language and I'm not mathematician, my origin are
Computer Sciences.<BR>I apologise in advance for rude errors I'll made, sooner
or later ;)</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Sequence definition:<BR>Different binary patterns
in the set of all permutations Sn taken modulo 2.<BR>Example: 0,1,2,3,4 modulo 2
= 0,1,0,1,0<BR>Short calculation gives
sequence:<BR>;N
0 1 2 3 4 5 6
7 8
9<BR>;
1, 2, 3, 6, 10, 20, 35, 70, 126<BR>;A001405: 1, 1, 2, 3, 6, 10, 20,
35, 70, 126, 252, 462, 924, 1716</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Recently, I thought that such binary patterns are
of use in the problem I'm researching.<BR>That assumption turned to be
wrong so I had no reason to go any deeper into that sequence.<BR>However, I'm
fairly confident that the sequence in question is A001405 indeed.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>What is your opinion, is it realy
A001405?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Reason why I'm posting this is:<BR>1. I see no
explicite corellation with permutations there, or I've overlooked
something.<BR>2. Sequence definition over Sn seems simplest than definition(s)
given in OEIS, <BR> from my point of view at least. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Is it worth of noting it there?<BR>If so, can you
assist me to do that. <BR>I do not pretend that my english and math terminology
is good enough.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Best regards,<BR>--ivica</FONT></DIV></BODY></HTML>