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Search: id:A120930
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| A120930 |
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Least x satisfying n^3 + x^3 + y^3 = z^3, where (n,x,y,z),n<x<y<z forms a primitive quadruple. |
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3
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| 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; listen)
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OFFSET
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1,1
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COMMENT
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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 (martin_n_fuller(AT)btinternet.com), Aug 11 2006
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LINKS
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S. Dutch, Cubic Quartets With a,b,c<1000
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PROGRAM
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(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 (martin_n_fuller(AT)btinternet.com), Aug 11 2006
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CROSSREFS
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Cf. A120931; A120932.
Sequence in context: A001143 A138490 A022510 this_sequence A070395 A112366 A095421
Adjacent sequences: A120927 A120928 A120929 this_sequence A120931 A120932 A120933
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KEYWORD
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nonn
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AUTHOR
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Lekraj Beedassy (blekraj(AT)yahoo.com), Jul 16 2006
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EXTENSIONS
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Corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 25 2006
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