A124969 Numbers which can be expressed as an ordered sum of 3 squares in 5 or more different ways.

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

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

Select[Range[434], Length@PowersRepresentations[#, 3, 2] >= 5 &] (* Ray Chandler, Oct 31 2019 *)

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