

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
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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[(nx)^(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



