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 A216284 Number of solutions to the equation x^4+y^4 = n with x >= y > 0. 4
 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,635318657 LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(n) <= A216280(n). - Antti Karttunen, Aug 28 2017 EXAMPLE From Antti Karttunen, Aug 28 2017: (Start) For n = 2 there is one solution: 2 = 1^4 + 1^4, thus a(2) = 1. For n = 17 there is one solution: 17 = 2^4 + 1^4, thus a(17) = 1. For n = 635318657 we have two solutions: 635318657 = 158^4 + 59^4 = 134^4 + 133^4, thus a(635318657) = 2. Note that this is the first point where the sequence attains value greater than 1. See Charles R Greathouse IV's Jan 12 2017 comment in A216280. (End) PROG (Scheme) (define (A216284 n) (let loop ((x (A255270 n)) (s 0)) (let* ((x4 (A000583 x)) (y4 (- n x4))) (if (< x4 y4) s (loop (- x 1) (+ s (if (and (> y4 0) (= (A000583 (A255270 y4)) y4)) 1 0))))))) ;; Antti Karttunen, Aug 28 2017 CROSSREFS Cf. A025455, A025446, A000161, A025426, A216280. Sequence in context: A063524 A326168 A033683 * A360109 A355452 A130638 Adjacent sequences: A216281 A216282 A216283 * A216285 A216286 A216287 KEYWORD nonn AUTHOR V. Raman, Sep 03 2012 EXTENSIONS Definition edited to match the given data and the second part of offset (635318657) explicitly added by Antti Karttunen, Aug 28 2017 STATUS approved

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Last modified April 19 19:02 EDT 2024. Contains 371798 sequences. (Running on oeis4.)