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Search: id:A124967
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| A124967 |
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Numbers which can be expressed as the ordered sum of 3 squares in 3 or more different ways. |
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+0
3
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| 41, 50, 54, 65, 66, 74, 81, 86, 89, 90, 98, 99, 101, 110, 113, 114, 117, 121, 122, 125, 126, 129, 131, 134, 137, 145, 146, 149, 150, 153, 161, 162, 164, 166, 169, 170, 171, 173, 174, 178, 179, 181, 182, 185, 186, 189, 194, 197, 198, 200, 201, 205, 206, 209
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(1)=41 because 41=4^2+4^2+3^2 or 5^2+4^2+0^2 or 6^2+2^2+1^2
117=0^2+6^2+9^2=1^2+4^2+10^2=2^2+7^2+8^2, so 117 is in the list.
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MATHEMATICA
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Needs["NumberTheory`NumberTheoryFunctions`"]; Select[Range[220], Length @ OrderedSumOfSquaresRepresentations[3, # ] >= 3 &] (*Chandler*)
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PROGRAM
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(PARI) isA124967(n)={ local(cnt=0, z2) ; for(x=0, floor(sqrt(n)), for(y=x, floor(sqrt(n-x^2)), z2=n-x^2-y^2 ; if( z2>=y^2 && issquare(z2), cnt++ ; ) ; if(cnt >=3, return(1) ) ; ) ; ) ; return(0) ; } { for(n=1, 200, if( isA124967(n), print1(n, ", ") ; ) ; ) ; } (Mathar)
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CROSSREFS
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Cf. A124966-A124971.
Sequence in context: A039383 A043206 A043986 this_sequence A052032 A115663 A118636
Adjacent sequences: A124964 A124965 A124966 this_sequence A124968 A124969 A124970
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Nov 14 2006
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EXTENSIONS
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Corrected and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net) and R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 29 2006
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