%I A006580 M3336
%S A006580 1,4,8,20,21,56,60,96,105,220,152,364,301,360,464,816,549,1140,760,
%T A006580 1036,1221,2024,1196,2200,2041,2484,2184,4060,2205,4960,3664,4224,
%U A006580 4641,5180,4008,8436,6517,7072,5980,11480,6321,13244,8888,9540,11661
%N A006580 Sum lcm { k,n-k }, k = 1 . . n-1.
%D A006580 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006580 Marc LeBrun (mlb(AT)well.com), personal communication.
%t A006580 Table[ Sum[ LCM[ k, n-k ], {k, 1, n-1} ], {n, 2, 50} ]
%Y A006580 Antidiagonal sums of array A003990.
%Y A006580 Sequence in context: A083579 A104626 A065034 this_sequence A061814 A087254 
               A160726
%Y A006580 Adjacent sequences: A006577 A006578 A006579 this_sequence A006581 A006582 
               A006583
%K A006580 nonn
%O A006580 2,2
%A A006580 N. J. A. Sloane (njas(AT)research.att.com).
%E A006580 More terms and Mathematica Program Aug 15 1997 (Olivier Gerard).