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 A175610 Numbers k such that k^4 = x^4 + y^4 + z^4, where x,y,z are positive integers. 8
 422481, 844962, 1267443, 1689924, 2112405, 2534886, 2813001, 2957367, 3379848, 3802329, 4224810, 4647291, 5069772, 5492253, 5626002, 5914734, 6337215, 6759696, 7182177, 7604658, 8027139, 8439003, 8449620, 8707481, 8872101, 9294582, 9717063, 10139544, 10562025, 10984506 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Main sequence is A003828. LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..4999 EXAMPLE a(1) = 422481 because 422481^4 = 95800^4 + 217519^4 + 414560^4. a(61) = 20615673 because 20615673^4 = 2682440^4 + 15365639^4 + 18796760^4. MATHEMATICA Select[Range[100], (p = PowersRepresentations[#^4, 3, 4]; (Select[p, #[[1]] > 0 && #[[2]] > 0 && #[[3]] > 0 &] != {})) &] (* Jinyuan Wang, Feb 20 2020 *) PROG (PARI) is(n) = for(a=sqrtnint(n^4\3, 4), n-1, for(b=1, a, for(c=1, b, if(n^4==a^4+b^4+c^4, return(1))))); 0; \\ Charles R Greathouse IV, Aug 29 2013 and slightly modified by Jinyuan Wang, Feb 20 2020 CROSSREFS Cf. A003337, A003828, A175598. Sequence in context: A202405 A264764 A130022 * A003828 A233722 A253958 Adjacent sequences:  A175607 A175608 A175609 * A175611 A175612 A175613 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Jul 24 2010 EXTENSIONS Terms and example corrected by Charles R Greathouse IV, Aug 29 2013 First 0 removed by Jinyuan Wang, Feb 20 2020 STATUS approved

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Last modified October 1 11:59 EDT 2020. Contains 337443 sequences. (Running on oeis4.)