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A120930 Least x satisfying n^3 + x^3 + y^3 = z^3, where (n,x,y,z),n<x<y<z forms a primitive quadruple. 2
6, 17, 4, 17, 76, 32, 14, 209, 55, 261, 15, 19, 51, 23, 42, 23, 40, 19, 53, 54, 43, 51, 81, 159, 31, 55, 30, 53, 34, 266, 33, 54, 70, 39, 77, 38, 174, 43, 146, 141, 114, 83, 230, 51, 53, 47, 75, 85, 80, 61, 82, 321, 58, 80, 113, 61, 68, 59, 93, 342, 90, 183, 228, 75, 87, 97 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

There are a few small cases where the least x needs y>1000, e.g. 8^3+209^3+1744^3=1745^3. The S. Dutch link has a few nonprimitive quartets which have to be excluded for this sequence, e.g. 37^3+222^3+296^3=333^3. - Martin Fuller, Aug 11 2006

LINKS

Table of n, a(n) for n=1..66.

S. Dutch, Cubic Quartets With a,b,c<1000

PROG

(PARI) A(n)=local(x, y, z); x=n+1; while(1, y=x+1; while(n^3+x^3+y^3>=(y+1)^3, if(ispower(n^3+x^3+y^3, 3, &z) && (gcd([n, x, y, z])==1), return(x)); y++; ); x++; ); \\ Martin Fuller, Aug 11 2006

CROSSREFS

Cf. A120931, A120932.

Sequence in context: A022510 A065776 A323516 * A070395 A200871 A112366

Adjacent sequences:  A120927 A120928 A120929 * A120931 A120932 A120933

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Jul 16 2006

EXTENSIONS

Corrected by R. J. Mathar, Nov 25 2006

STATUS

approved

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Last modified October 23 22:52 EDT 2019. Contains 328378 sequences. (Running on oeis4.)