%I
%S 1,1,2,2,3,3,4,4,5,4,4,3,4,3,5,4,7,6,10,9,14,13,19,18,25,24,32,31,
%T 40,38,38,36,37,35,37,35,38,36,40,38,43,41,47,45,52,50,58,56,65,62,62,
%U 59,60,57,59,56,59,56,60,57,62,59,65,62,69,66,74,71,80,76,76,72,73,69
%N a(n) is the number obtained by writing out numbers from 1 to n and placing an alternate + and  minus sign between successive digits and evaluating the expression written.
%H Sphere Online Judge, <a href="http://www.spoj.pl/problems/KPSUM/">Problem 1433: The Sum</a> [Link edited by _N. J. A. Sloane_, Nov 02 2009]
%F a(n) = sum_{i=1..n} (1)^i*A007376(i). [From _R. J. Mathar_, Nov 09 2009]
%K sign,base
%O 1,3
%A Dhruv (dhruvbird(AT)gmail.com), Oct 31 2009
%E a(12) corrected, more terms appended by _R. J. Mathar_, Nov 09 2009
