login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A088687 Numbers that can be represented as j^4 + k^4, with 0 < j < k, in exactly one way. 9
17, 82, 97, 257, 272, 337, 626, 641, 706, 881, 1297, 1312, 1377, 1552, 1921, 2402, 2417, 2482, 2657, 3026, 3697, 4097, 4112, 4177, 4352, 4721, 5392, 6497, 6562, 6577, 6642, 6817, 7186, 7857, 8962, 10001, 10016, 10081, 10256, 10625, 10657, 11296 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..42.

EXAMPLE

17 = 1^4 + 4^4.

635318657 = 133^4 + 134^4 is absent because it is also 59^4 + 158^4 (see A046881, A230562)

MATHEMATICA

lst={}; Do[Do[x=a^4; Do[y=b^4; If[x+y==n, AppendTo[lst, n]], {b, Floor[(n-x)^(1/4)], a+1, -1}], {a, Floor[n^(1/4)], 1, -1}], {n, 4*7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jan 22 2009 *)

PROG

(PARI) powers2(m1, m2, p1) = { for(k=m1, m2, a=powers(k, p1); if(a==1, print1(k", ")) ); } powers(n, p) = { z1=0; z2=0; c=0; cr = floor(n^(1/p)+1); for(x=1, cr, for(y=x+1, cr, z1=x^p+y^p; if(z1 == n, c++); ); ); return(c) }

CROSSREFS

Cf. A003336, A088728.

Sequence in context: A197397 A053826 A184982 * A321560 A034678 A065960

Adjacent sequences:  A088684 A088685 A088686 * A088688 A088689 A088690

KEYWORD

nonn

AUTHOR

Cino Hilliard, Nov 22 2003

EXTENSIONS

Edited by Don Reble, May 03 2006

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 11 18:19 EST 2019. Contains 329925 sequences. (Running on oeis4.)