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Search: id:A161992
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| A161992 |
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Numbers which squared are a sum of 3 distinct non-zero squares. |
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+0
3
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| 7, 9, 11, 13, 14, 15, 17, 18, 19, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Square roots of squares in A004432. - R. J. Mathar, Sep 22 2009
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EXAMPLE
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7^2=2^2+3^2+6^2. 9^2=1^2+4^2+8^2. 11^2 = 2^2+6^2+9^2. 15^2=2^2+5^2+14^2.
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MAPLE
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isA004432 := proc(n) local x, y, z2 ; for x from 1 do if x^2 > n then break; fi; for y from 1 to x-1 do z2 := n-x^2-y^2 ; if z2 < y^2 and z2 > 0 then if issqr(z2) then RETURN(true) ; fi; fi; od: od: false ; end:
isA161992 := proc(n) isA004432(n^2) ; end:
for n from 1 do if isA161992(n) then printf("%d\n", n) ; fi; od: # R. J. Mathar, Sep 22 2009
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MATHEMATICA
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lst={}; Do[Do[Do[a=(x^2+y^2+z^2)^(1/2); If[a==IntegerPart[a], AppendTo[lst, a]], {z, y+1, 2*5!}], {y, x+1, 2*5!}], {x, 5!}]; lst; q=Take[Union[%], 150]
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CROSSREFS
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Cf. A029747
Sequence in context: A058483 A162308 A108815 this_sequence A167377 A004169 A066669
Adjacent sequences: A161989 A161990 A161991 this_sequence A161993 A161994 A161995
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KEYWORD
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nonn
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Jun 24 2009
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EXTENSIONS
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Definition rephrased by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 22 2009
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