Many excellent designs for a new banner were submitted. We will use the best of them in rotation.
1,2
Lars Blomberg, Table of n, a(n) for n = 1..10000
Lars Blomberg, C# program for calculating b-file
a(n) = 2*A049988(n) - A000005(n).
G.f.: x/(1-x) + Sum_{k>=2} x^k * (1 + x^(k(k-1)/2)) / (1 - x^(k(k-1)/2)) / (1 -x^k).
Cf. A049988, A175327.
Sequence in context: A136585 A122721 A014224 * A077312 A140779 A117890
Adjacent sequences: A175339 A175340 A175341 * A175343 A175344 A175345
nonn
Leroy Quet, Apr 17 2010
Edited and extended by Max Alekseyev, May 03 2010
approved
