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Search: id:A002859
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| A002859 |
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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.
(Formerly M2303 N0909)
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+0
8
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| 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, 83, 98, 99, 101, 110, 114, 121, 125, 132, 136, 139, 143, 145, 152, 161, 165, 172, 176, 187, 192, 196, 201, 205, 212, 216, 223, 227, 232, 234, 236, 243, 247, 252, 256, 258
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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An Ulam-type sequence - see A002858 for many further references, comments, etc.
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 145-151.
R. K. Guy, Unsolved Problems in Number Theory, Section C4.
R. K. Guy, ``s-Additive sequences,'' preprint, 1994.
C. Pickover, Mazes for the Mind, St. Martin's Press, NY, 1992, p. 358.
R. Queneau, Sur les suites s-additives, J. Combin. Theory, A12 (1972), 31-71.
S. M. Ulam, Problems in Modern Mathematics, Wiley, NY, 1960, p. ix.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
S. R. Finch, Ulam s-Additive Sequences
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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EXAMPLE
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7 is missing since 7=1+6=3+4; but 8 is present since 8=3+5 has a unique representation.
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CROSSREFS
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Adjacent sequences: A002856 A002857 A002858 this_sequence A002860 A002861 A002862
Sequence in context: A051916 A130216 A120162 this_sequence A062514 A065875 A100585
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein
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