[seqfan] Re: Exit

[RGWv]

?Et al,

I nominate the sequence A036057, "Friedman numbers: can be written in a 
nontrivial way using their digits and the operations + - * / ^ and 
concatenation of digits (but not of results)" as Sequence of the Day for 
January 1, 2011.

It is the quintessential sequence for recreational mathematics connected to 
the years and how they can be generated from either its own digits (as per 
the Friedman numbers) or from a list of the integers (as per Hans 
Havermann's email today). Its too bad that 2011 is not in the sequence.

I think that Charles W. Triggs would have been pleased with this sequence.

Bob.

-----Original Message----- 
From: Hans Havermann
Sent: Wednesday, December 29, 2010 12:17 PM
To: Sequence Fanatics Discussion list
Subject: [seqfan] Re: Exit

Eric Angelini:

> ... and welcome to 0+1*2345*6/7-8+9

:) Disallowing a leading zero on a number, I make this one of 12
solutions (standard order of operations apply):

0+1-2*3+4*567*8/9
0+1*2345*6/7-8+9
0+1*2/3*45*67-8+9
0+1/2*3*4*5*67-8+9
0-12+345*6-7*8+9
0-1*2-3+4*567*8/9
0*1+2345*6/7-8+9
0*1+2/3*45*67-8+9
0*1-2-3+4*567*8/9
0/1+2345*6/7-8+9
0/1+2/3*45*67-8+9
0/1-2-3+4*567*8/9

... and 22 solutions, if we move the zero to the end:

1+2345*6/7+89*0
1+2345*6/7+8*9*0
1+2345*6/7+8/9*0
1+2345*6/7-89*0
1+2345*6/7-8*9*0
1+2345*6/7-8/9*0
1+2/3*45*67+89*0
1+2/3*45*67+8*9*0
1+2/3*45*67+8/9*0
1+2/3*45*67-89*0
1+2/3*45*67-8*9*0
1+2/3*45*67-8/9*0
1-2*3+4*567*8/9+0
1-2*3+4*567*8/9-0
1*2345*6/7-8+9+0
1*2345*6/7-8+9-0
1*23+45*6*7+8+90
1*2+34*56+7+8+90
1*2/3*45*67-8+9+0
1*2/3*45*67-8+9-0
1/2*3*4*5*67-8+9+0
1/2*3*4*5*67-8+9-0


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