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A152044
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Numbers expressible as the difference of two nonnegative fourth powers.
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4
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0, 1, 15, 16, 65, 80, 81, 175, 240, 255, 256, 369, 544, 609, 624, 625, 671, 1040, 1105, 1215, 1280, 1295, 1296, 1695, 1776, 2145, 2320, 2385, 2400, 2401, 2465, 2800, 3439, 3471, 3840, 4015, 4080, 4095, 4096, 4160, 4641, 5265, 5904, 5936, 6095, 6305, 6480
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OFFSET
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1,3
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COMMENTS
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LINKS
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EXAMPLE
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E.g. 15=2^4-1^4, 175=4^4-3^4
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MATHEMATICA
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Select[Abs[Differences/@Tuples[Range[0, 12]^4, 2]]//Flatten//Union, #<= 6500&] (* Harvey P. Dale, Sep 14 2020 *)
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PROG
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(PARI) is(n)=if(n<1, return(!n)); for(m=sqrtnint(n-1, 4)+1, sqrtnint(n\4, 3)+1, if(ispower(m^4-n, 4), return(1))); 0 \\ Charles R Greathouse IV, Sep 04 2013
(PARI) lst(lim)=my(v=List([0]), t); lim\=1; for(n=1, sqrtnint(lim\4, 3)+1, for(m=sqrtnint(max(n^4-lim, 0), 4), n-1, t=n^4-m^4; if(t<=lim, listput(v, t)))); vecsort(Vec(v), , 8) \\ Charles R Greathouse IV, Sep 04 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Mark Taggart (mt2612f(AT)aol.com), Nov 21 2008
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EXTENSIONS
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STATUS
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approved
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