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Search: id:A029745
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| A029745 |
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Numbers of the form 2^n or 5*2^n. |
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+0
2
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| 1, 2, 8, 5, 16, 10, 32, 20, 64, 40, 128, 80, 256, 160, 512, 320, 1024, 640, 2048, 1280, 4096, 2560, 8192, 5120, 16384, 10240, 32768, 20480, 65536, 40960, 131072, 81920, 262144, 163840, 524288, 327680, 1048576, 655360, 2097152, 1310720, 4194304
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The only natural numbers which cannot be the lengths of an interior diagonal of a cuboid with natural edges. - Michael Somos Mar 02 2004
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REFERENCES
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W. Sierpinski, Pythagorean triangles, Dover Publications, Inc., Mineola, NY, 2003, p. 101 MR2002669
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FORMULA
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G.f.: (1+2x+6x^2+x^3)/(1-2x^2).
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PROGRAM
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(PARI) a(n)=if(n<2, 1+max(-1, n), 2^(n\2)*if(n%2, 5/2, 4))
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CROSSREFS
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Cf. A094958.
Adjacent sequences: A029742 A029743 A029744 this_sequence A029746 A029747 A029748
Sequence in context: A115319 A122387 A021039 this_sequence A096417 A011059 A019771
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KEYWORD
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nonn
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AUTHOR
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njas
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