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A038593 Differences between positive cubes in 1, 2 or 3 ways: union of A014439, A014440 and A014441. 44
7, 19, 26, 37, 56, 61, 63, 91, 98, 117, 124, 127, 152, 169, 189, 208, 215, 217, 218, 271, 279, 296, 316, 331, 335, 342, 386, 387, 397, 448, 469, 485, 488, 504, 511, 513, 547, 602, 604, 631, 657, 665, 702, 721, 728, 784, 817, 819, 866, 875, 919, 936, 973, 988 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MAPLE
N:= 1000: # to get all terms <= N
X:= floor(sqrt(N/3)):
V:= Vector(N):
for x from 2 to X do
if x^3 > N then
y0:= iroot(x^3-N, 3);
if x^3 - y0^3 > N then y0:= y0+1 fi;
else y0:= 1 fi;
for y from y0 to x-1 do
V[x^3 - y^3] := V[x^3 - y^3]+1
od
od:
select(t -> V[t] <= 3 and V[t]>=1, [$1..N]); # Robert Israel, Dec 10 2015
MATHEMATICA
r = 988; p = 3; Sort@Drop[Flatten@Select[Tally@Reap[Do[n = i^p - j^p; If[n <= r, Sow[n]], {i, Ceiling[(r/p)^(1/(p - 1))]}, {j, i}]][[2, 1]], 0 < #[[2]] < 4 &], {2, -1, 2}] (* Arkadiusz Wesolowski, Dec 10 2015 *)
CROSSREFS
Sequence in context: A003282 A006063 A181123 * A014439 A342160 A175376
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected by Don Reble, Nov 19 2006
STATUS
approved

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Last modified April 15 20:47 EDT 2024. Contains 371696 sequences. (Running on oeis4.)