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A005244
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A self-generating sequence: start with 2 and 3, take all products of any 2 previous elements, subtract 1 and adjoin them to the sequence.
(Formerly M0704)
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6
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2, 3, 5, 9, 14, 17, 26, 27, 33, 41, 44, 50, 51, 53, 65, 69, 77, 80, 81, 84, 87, 98, 99, 101, 105, 122, 125, 129, 131, 134, 137, 149, 152, 153, 158, 159, 161, 164, 167, 173, 194, 195, 197, 201, 204, 206, 209, 219, 230, 233, 237, 239, 242, 243, 249
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n)=A139127(n)*a(k)-1 for some k; A139128 gives number of distinct representations a(n)=a(i)*a(j)-1. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 09 2008
Complement of A171413. [From Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Dec 08 2009]
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REFERENCES
| R. K. Guy, Unsolved Problems in Number Theory, E31.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| R. Zumkeller, Table of n, a(n) for n = 1..500
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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EXAMPLE
| 17 is present because it equals 2*9-1.
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MATHEMATICA
| f[s_, mx_] := Union[s, Select[Apply[Times, Subsets[s, {2}], {1}] - 1, # <= mx &]]; mx = 250; FixedPoint[f[#, mx] &, {2, 3}] (* From Jean-François Alcover , Mar 29 2011 *)
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CROSSREFS
| Sequence in context: A057225 A070819 A195667 * A058541 A023672 A023567
Adjacent sequences: A005241 A005242 A005243 * A005245 A005246 A005247
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KEYWORD
| nonn,nice,easy
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AUTHOR
| D. R. Hofstadter
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EXTENSIONS
| More terms from Jud McCranie (JudMcCranie(AT)ugaalum.uga.edu)
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