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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 * A130638 A030217 A030215

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 October 22 22:35 EDT 2021. Contains 348180 sequences. (Running on oeis4.)