%I A087156
%S A087156 0,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,
%T A087156 26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,
%U A087156 48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,
               71,72,73,74,75,76,77
%N A087156 Nonnegative numbers excluding 1.
%C A087156 The old entry with this sequence number was a duplicate of A026835.
%C A087156 A063524(a(n)) = 0. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), 
               Oct 11 2008]
%C A087156 Inverse binomial transform of A006589 . [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), 
               Nov 25 2008]
%C A087156 a(n) = maximum value of j, where 1 <= j <= n-1, such that floor(j^2 / 
               n) > 0 for each n.
%F A087156 G.f.: x^2*(2-x)/(1-x)^2 . E.g.f.: x*(exp(x)-1). [From Philippe DELEHAM 
               (kolotoko(AT)wanadoo.fr), Nov 25 2008]
%F A087156 a(n)=A163300(n)/2. [From Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), 
               Aug 14 2009]
%F A087156 a(n)=n-1+[(n+1) mod n], with n>=1 [From Paolo P. Lava (ppl(AT)spl.at), 
               Nov 06 2009]
%F A087156 a(n)=n mod sigma_k(n), where sigma_k is the k divisor sigma function 
               [From Barbarel Tres Mil (barbarel3000(AT)yahoo.es), Nov 11 2009]
%t A087156 A087156[n_] := Mod[n, DivisorSigma[1, n]] [From Barbarel Tres Mil (barbarel3000(AT)yahoo.es), 
               Nov 11 2009]
%Y A087156 Cf. A000027.
%Y A087156 Cf. A166373.
%Y A087156 Sequence in context: A131738 A000027 A001477 this_sequence A033619 A130734 
               A090108
%Y A087156 Adjacent sequences: A087153 A087154 A087155 this_sequence A087157 A087158 
               A087159
%K A087156 nonn,new
%O A087156 1,2
%A A087156 N. J. A. Sloane (njas(AT)research.att.com), Oct 11 2008
%E A087156 Comment and cross-reference added by Christopher Hunt Gribble (chris.eveswell(AT)virgin.net), 
               Oct 14 2009, Oct 17 2009