A135986 - OEIS

%I #8 Sep 16 2015 13:28:04

%S 1,3,3,6,4,8,6,10,7,11,9,15,13,17,17,22,20,26,24,30,26,26,24,32,29,33,

%T 33,39,37,45,43,49,45,45,45,54,52,56,56,64,62,70,68,74,74,70,68,78,75,

%U 81,77,83,81,89,85,93,89,89,87,99,97,101,107,114,110,118,116,122,118

%N a(1)=1; a(n) = a(n-1) + d(n) if d(n) > d(n-1); a(n) = a(n-1) - d(n) if d(n) < d(n-1); a(n) = a(n-1) if d(n) = d(n-1), where d = A000005.

%t a = {1}; For[n = 2, n < 70, n++, If[DivisorSigma[0, n] > DivisorSigma[0, n - 1], AppendTo[a, a[[ -1]] + DivisorSigma[0, n]], If[DivisorSigma[0, n] < DivisorSigma[ 0, n - 1], AppendTo[a, a[[ -1]] - DivisorSigma[0, n]], AppendTo[a, a[[ -1]]]]]]; a (* _Stefan Steinerberger_, Oct 20 2008 *)

%Y Cf. A000005.

%K nonn

%O 1,2

%A _Leroy Quet_, Mar 02 2008

%E More terms from _Stefan Steinerberger_, Oct 20 2008