A003380 Numbers that are the sum of 2 nonzero 8th powers.

2, 257, 512, 6562, 6817, 13122, 65537, 65792, 72097, 131072, 390626, 390881, 397186, 456161, 781250, 1679617, 1679872, 1686177, 1745152, 2070241, 3359232, 5764802, 5765057, 5771362, 5830337, 6155426, 7444417, 11529602, 16777217, 16777472, 16783777, 16842752

Offset

1,1

Links

David A. Corneth, Table of n, a(n) for n = 1..10000 (first 5833 terms from R. J. Mathar, replacing an earlier b-file that was missing terms)

Example

From David A. Corneth, Aug 01 2020: (Start)
274893519322337 is in the sequence as 274893519322337 = 58^8 + 59^8.
357707312890625 is in the sequence as 357707312890625 = 50^8 + 65^8.
2590188068194497 is in the sequence as 2590188068194497 = 57^8 + 84^8. (End)

Maple

A003380 := proc(nmax::integer)
    local a, x, x8, y, y8 ;
    a := {} ;
    for x from 1 do
        x8 := x^8 ;
        if 2*x8 > nmax then
            break;
        end if;
        for y from x do
            y8 := y^8 ;
            if x8+y8 > nmax then
                break;
            end if;
            if x8+y8 <= nmax then
                a := a  union {x8+y8} ;
            end if;
        end do:
    end do:
    sort(convert(a, list)) ;
end proc:
nmax := 20000000000000000 ;
L:= A003380(nmax) ;
LISTTOBFILE(L, "b003380.txt", 1) ; # R. J. Mathar, Aug 01 2020

Mathematica

Total/@Tuples[Range[8]^8, 2]//Union (* Harvey P. Dale, Apr 04 2017 *)

Prog

(PARI) list(lim)=my(v=List(), x8); for(x=1, sqrtnint(lim\=1, 8), x8=x^8; for(y=1, min(sqrtnint(lim-x8, 8), x), listput(v, x8+y^8))); Set(v) \\ Charles R Greathouse IV, Aug 22 2017

Crossrefs

Subsequence of A004875.

Cf. A155468 (2 distinct 8th).

A###### (x, y): Numbers that are the form of x nonzero y-th powers.

Cf. A000404 (2, 2), A000408 (3, 2), A000414 (4, 2), A003072 (3, 3), A003325 (3, 2), A003327 (4, 3), A003328 (5, 3), A003329 (6, 3), A003330 (7, 3), A003331 (8, 3), A003332 (9, 3), A003333 (10, 3), A003334 (11, 3), A003335 (12, 3), A003336 (2, 4), A003337 (3, 4), A003338 (4, 4), A003339 (5, 4), A003340 (6, 4), A003341 (7, 4), A003342 (8, 4), A003343 (9, 4), A003344 (10, 4), A003345 (11, 4), A003346 (12, 4), A003347 (2, 5), A003348 (3, 5), A003349 (4, 5), A003350 (5, 5), A003351 (6, 5), A003352 (7, 5), A003353 (8, 5), A003354 (9, 5), A003355 (10, 5), A003356 (11, 5), A003357 (12, 5), A003358 (2, 6), A003359 (3, 6), A003360 (4, 6), A003361 (5, 6), A003362 (6, 6), A003363 (7, 6), A003364 (8, 6), A003365 (9, 6), A003366 (10, 6), A003367 (11, 6), A003368 (12, 6), A003369 (2, 7), A003370 (3, 7), A003371 (4, 7), A003372 (5, 7), A003373 (6, 7), A003374 (7, 7), A003375 (8, 7), A003376 (9, 7), A003377 (10, 7), A003378 (11, 7), A003379 (12, 7), A003380 (2, 8), A003381 (3, 8), A003382 (4, 8), A003383 (5, 8), A003384 (6, 8), A003385 (7, 8), A003387 (9, 8), A003388 (10, 8), A003389 (11, 8), A003390 (12, 8), A003391 (2, 9), A003392 (3, 9), A003393 (4, 9), A003394 (5, 9), A003395 (6, 9), A003396 (7, 9), A003397 (8, 9), A003398 (9, 9), A003399 (10, 9), A004800 (11, 9), A004801 (12, 9), A004802 (2, 10), A004803 (3, 10), A004804 (4, 10), A004805 (5, 10), A004806 (6, 10), A004807 (7, 10), A004808 (8, 10), A004809 (9, 10), A004810 (10, 10), A004811 (11, 10), A004812 (12, 10), A004813 (2, 11), A004814 (3, 11), A004815 (4, 11), A004816 (5, 11), A004817 (6, 11), A004818 (7, 11), A004819 (8, 11), A004820 (9, 11), A004821 (10, 11), A004822 (11, 11), A004823 (12, 11), A047700 (5, 2).

Sequence in context: A325051 A240551 A078168 * A259310 A060890 A294275

Adjacent sequences: A003377 A003378 A003379 * A003381 A003382 A003383

Keyword

nonn,easy,changed

Author

N. J. A. Sloane

Status

approved