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A255351
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Values of b = max {a,b,c,d} for solutions to a^4 + b^4 = c^4 + d^4, a < c < d < b, ordered by size of b.
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5
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158, 239, 292, 316, 474, 478, 502, 542, 584, 631, 632, 717, 790, 876, 948, 956, 1004, 1084, 1106, 1168, 1195, 1203, 1262, 1264, 1381, 1422, 1434, 1460, 1506, 1580, 1626, 1673, 1738, 1752, 1893, 1896, 1912
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OFFSET
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1,1
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COMMENTS
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See A018786 for the values of a^4 + b^4 = c^4 + d^4, and A255352 for the list of the full quadruples (a,b,c,d). See there for further comments, motivation and references.
The values of b listed here allow one to reproduce the full solutions (a,b,c,d) with not too much effort, cf. the inner loops of the PARI code.
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LINKS
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EXAMPLE
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The quadruples [a,b,c,d] are, listed in order of increasing b = max{a,b,c,d}):
[59, 158, 133, 134], [7, 239, 157, 227], [193, 292, 256, 257], [118, 316, 266, 268], [177, 474, 399, 402], [14, 478, 314, 454], [271, 502, 298, 497], [103, 542, 359, 514], [386, 584, 512, 514], [222, 631, 503, 558], [236, 632, 532, 536], [21, 717, 471, 681], [295, 790, 665, 670], [579, 876, 768, 771], [354, 948, 798, 804], [28, 956, 628, 908], ...
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PROG
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(PARI) {n=4; for(b=1, 1999, for(a=1, b, t=a^n+b^n; for(c=a+1, sqrtn(t\2, n), ispower(t-c^n, n)||next; print1(b", "); next(3))))}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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