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A003369

Numbers that are the sum of 2 positive 7th powers.

2, 129, 256, 2188, 2315, 4374, 16385, 16512, 18571, 32768, 78126, 78253, 80312, 94509, 156250, 279937, 280064, 282123, 296320, 358061, 559872, 823544, 823671, 825730, 839927, 901668, 1103479, 1647086, 2097153, 2097280, 2099339, 2113536

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OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

From David A. Corneth, Aug 03 2020: (Start)

3909794986386 is in the sequence as 3909794986386 = 57^7 + 57^7.

6061605477062 is in the sequence as 6061605477062 = 19^7 + 67^7.

26019535290982 is in the sequence as 26019535290982 = 61^7 + 81^7. (End)

MAPLE

N:= 10^7: # to get all terms <= N

S:= select(`<=`, {seq(seq(a^7+b^7, a=1..b), b=1..floor(N^(1/7)))}, N):

sort(convert(S, list)); # Robert Israel, Sep 03 2017

MATHEMATICA

lst={}; Do[If[(a^7+b^7)==n, AppendTo[lst, n]], {n, 200000}, {a, (n/2)^(1/7)}, {b, a, (n-a^7)^(1/7)}]; lst (* XU Pingya, Sep 03 2017 *)

Module[{upto=10}, Select[Union[Total/@Tuples[Range[upto]^7, 2]], #<= (upto^7)&]] (* Harvey P. Dale, Feb 04 2019 *)

CROSSREFS

Cf. A000404 (2 squares), A003325 (2 cubes), A003336 (2 4th), A003347 (2 5th), A003358 (2 6th), A088719 (2 distinct 7th), A003380 (2 8th).

Cf. A001015 (seventh powers).

Sequence in context: A153425 A296060 A090121 * A303377 A342618 A258806

Adjacent sequences: A003366 A003367 A003368 * A003370 A003371 A003372

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

URL: https://oeis.org/A003369

⇱ A003369 - OEIS