A099178 - OEIS

%I #9 Jun 13 2020 02:39:34

%S 1241,1343,1547,1853,2261,2771,3383,4097,9826,9928,10234,10744,11458,

%T 12376,13498,14824,16354,18088,20026,22168,24514,27064,29818,32776,

%U 33201,33507,34119,35037,35938,36261,37791,39627,41769,44217,46971

%N Numbers which are the sum of two positive cubes and divisible by 17.

%H Vincenzo Librandi, <a href="/A099178/b099178.txt">Table of n, a(n) for n = 1..1000</a>

%e Sums not divisible by 17 are indicated in asterisks:

%e ....|...1....8...27...64...125...216...343...512...729..1000..1331

%e ------------------------------------------------------------------

%e 1...|...*....*....*....*.....*.....*.....*.....*.....*.....*.....*

%e 8...|...*....*....*....*.....*.....*.....*.....*.....*.....*.....*

%e 27..|...*....*....*....*.....*.....*.....*.....*.....*.....*.....*

%e 64..|...*....*....*....*.....*.....*.....*.....*.....*.....*.....*

%e 125.|...*....*....*....*.....*.....*.....*.....*.....*.....*.....*

%e 216.|...*....*....*....*.....*.....*.....*.....*.....*.....*..1547

%e 343.|...*....*....*....*.....*.....*.....*.....*.....*..1343.....*

%e 512.|...*....*....*....*.....*.....*.....*.....*...1241....*.....*

%e 729.|...*....*....*....*.....*.....*.....*..1241.....*.....*.....*

%e 1000|...*....*....*....*.....*.....*..1343.....*.....*.....*.....*

%e 1331|...*....*....*....*.....*..1547.....*.....*.....*.....*.....*

%t upto[n_] := Block[{t}, Union@ Reap[ Do[If[Mod[t = x^3 + y^3, 17] == 0, Sow@t], {x, n^(1/3)}, {y, Min[x, (n - x^3)^(1/3)]}]][[2, 1]]]; upto[47000] (* _Giovanni Resta_, Jun 12 2020 *)

%Y Cf. A098365.

%K nonn,easy

%O 1,1

%A Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Nov 15 2004