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A124969 Numbers which can be expressed as an ordered sum of 3 squares in 5 or more different ways. 2
146, 153, 185, 194, 206, 209, 221, 225, 230, 234, 257, 261, 266, 269, 281, 290, 293, 297, 305, 306, 314, 321, 325, 326, 329, 338, 341, 342, 350, 353, 354, 362, 365, 369, 374, 377, 381, 386, 389, 398, 401, 402, 405, 409, 410, 413, 414, 419, 425, 426, 434 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Ray Chandler, Table of n, a(n) for n = 1..10000

EXAMPLE

a(1)=146 because 146=9^2+7^2+4^2 = 9^2+8^2+1^2 = 11^2+4^2+3^2 = 11^2+5^2+0^2 = 12^2+1^2+1^2

185=0^2+4^2+13^2=0^2+8^2+11^2=2^2+9^2+10^2=4^2+5^2+12^2=6^2+7^2+10^2, so 185 is in the list.

MATHEMATICA

Needs["NumberTheory`NumberTheoryFunctions`"]; Select[Range[450], Length @ OrderedSumOfSquaresRepresentations[3, # ] >= 5 &] (*Chandler*)

PROG

(PARI) isA124969(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 >=5, return(1) ) ; ) ; ) ; return(0) ; } { for(n=1, 800, if( isA124969(n), print1(n, ", ") ; ) ; ) ; } - R. J. Mathar, Dec 07 2006

CROSSREFS

Cf. A124966-A124971.

Sequence in context: A015081 A015055 A166071 * A294594 A031510 A145915

Adjacent sequences:  A124966 A124967 A124968 * A124970 A124971 A124972

KEYWORD

nonn

AUTHOR

Artur Jasinski, Nov 14 2006

EXTENSIONS

Corrected and extended by Ray Chandler and R. J. Mathar, Nov 29 2006

STATUS

approved

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Last modified January 16 21:37 EST 2019. Contains 319206 sequences. (Running on oeis4.)