%I A002859 M2303 N0909
%S A002859 1,3,4,5,6,8,10,12,17,21,23,28,32,34,39,43,48,52,54,59,63,68,72,74,79,
%T A002859 83,98,99,101,110,114,121,125,132,136,139,143,145,152,161,165,172,176,
%U A002859 187,192,196,201,205,212,216,223,227,232,234,236,243,247,252,256,258
%N A002859 a(1)=1, a(2)=3; for n >= 3, a(n) is smallest number which is uniquely 
               of the form a(j)+a(k) with 1<=j<k<n.
%C A002859 An Ulam-type sequence - see A002858 for many further references, comments, 
               etc.
%D A002859 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A002859 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A002859 S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 145-151.
%D A002859 R. K. Guy, Unsolved Problems in Number Theory, Section C4.
%D A002859 R. K. Guy, ``s-Additive sequences,'' preprint, 1994.
%D A002859 C. Pickover, Mazes for the Mind, St. Martin's Press, NY, 1992, p. 358.
%D A002859 R. Queneau, Sur les suites s-additives, J. Combin. Theory, A12 (1972), 
               31-71.
%D A002859 S. M. Ulam, Problems in Modern Mathematics, Wiley, NY, 1960, p. ix.
%H A002859 T. D. Noe, <a href="b002859.txt">Table of n, a(n) for n=1..10000</a>
%H A002859 S. R. Finch, <a href="http://algo.inria.fr/bsolve/constant/stlrsky/sadd/
               sadd.html">Ulam s-Additive Sequences</a>
%H A002859 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               UlamSequence.html">Link to a section of The World of Mathematics.</
               a>
%e A002859 7 is missing since 7=1+6=3+4; but 8 is present since 8=3+5 has a unique 
               representation.
%Y A002859 Sequence in context: A051916 A130216 A120162 this_sequence A062514 A065875 
               A167057
%Y A002859 Adjacent sequences: A002856 A002857 A002858 this_sequence A002860 A002861 
               A002862
%K A002859 nonn,nice
%O A002859 1,2
%A A002859 N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein