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a(n) = number of ways of placing '+' and '-' among the digits 123456789 so that the result of the expression is n, '-' before 1 IS allowed.
6

%I #7 Mar 30 2012 18:50:19

%S 22,43,18,41,18,40,24,39,18,46,17,38,27,38,24,43,18,39,23,37,23,43,25,

%T 36,32,36,25,44,25,35,34,31,26,37,24,35,32,32,27,37,31,26,34,34,29,42,

%U 27,27,35,26,28,35,29,33,30,26,23,29,32,25,33,30,24,34,22,26,32,30,25

%N a(n) = number of ways of placing '+' and '-' among the digits 123456789 so that the result of the expression is n, '-' before 1 IS allowed.

%C A066957(9)=46 is the largest term; A066957(456789)=2 is the last term greater than 1; a(n)=0 for n>123456789; 1715 terms are greater than 0; a(A136601(n))=0; a(A136602(n))>0; a(A136603(n))=1; partial sums are A136604. - _Reinhard Zumkeller_, Jan 12 2008

%H R. Zumkeller, <a href="/A066957/b066957.txt">Table of n, a(n) for n = 0..10000</a>

%H R. Zumkeller, <a href="/A066957/a066957.txt">Illustration of initial terms</a>

%Y Cf. A066956.

%K nice,nonn,base

%O 0,1

%A Miklos SZABO (mike(AT)ludens.elte.hu), Feb 01 2002