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Search: id:A046727
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| 0, 3, 21, 119, 697, 4059, 23661, 137903, 803761, 4684659, 27304197, 159140519, 927538921, 5406093003, 31509019101, 183648021599, 1070379110497, 6238626641379, 36361380737781, 211929657785303, 1235216565974041
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OFFSET
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0,2
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COMMENT
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For a triple (a,b,c) there exist k,m such that (a,b,c) = (k^2-m^2, 2km, k^2+m^2). Here k = A001333(n) and m = A001333(n+1), so this sequence is identical to the Pell oblongs A084159 for n>0. - Lambert Klasen (Lambert.Klasen(AT)gmx.de), Nov 10 2004
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REFERENCES
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A. H. Beiler, Recreations in the Theory of Numbers. New York: Dover, pp. 122-125, 1964.
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LINKS
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A. Bogomolny, The Trinary Tree(s) underlying Primitive Pythagorean Triples.
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FORMULA
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Values of x obtained by repeatedly multiplying the triple (x, y, z)=(3, 4, 5) by the matrix A = ([1 2 2] [2 1 2] [2 2 3]), the Across matrix of "The Trinary Tree(s) underlying Primitive Pythagorean Triples" generating matrices. - Vim Wenders (vim(AT)gmx.li), Jan 14 2004
For n>0 a(n)=A001333(n)*A001333(n+1) - Lambert Klasen (Lambert.Klasen(AT)gmx.de), Nov 10 2004
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CROSSREFS
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Cf. A046729. Essentially the same as A084159.
Adjacent sequences: A046724 A046725 A046726 this_sequence A046728 A046729 A046730
Sequence in context: A121140 A005057 A092634 this_sequence A084159 A117512 A068127
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KEYWORD
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easy,nonn
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AUTHOR
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njas
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EXTENSIONS
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More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Jan 23 2003
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