A228946 Numbers n such that n^3-k^3 is a square for some k<n, k>0.

8, 10, 14, 28, 32, 33, 40, 56, 57, 65, 71, 72, 74, 78, 90, 105, 112, 114, 126, 128, 130, 132, 140, 148, 154, 155, 160, 176, 193, 200, 217, 218, 224, 228, 250, 252, 260, 266, 273, 280, 284, 288, 296, 297, 305, 312, 329, 336, 344, 349, 350, 360, 392

Offset

1,1

Comments

See A038596 = A038597^2 for the possible values of n^3-k^3.

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..5000

Maple

isA228946 := proc (n) local k; for k to n-1 do if issqr(n^3-k^3) then return true end if end do; return false end proc; for n from 1 to 400 do if isA228946(n)then print(n): end if: end do: # Nathaniel Johnston, Oct 07 2013

Mathematica

k3sQ[n_]:=Count[n^3-Range[n-1]^3, _?(IntegerQ[Sqrt[#]]&)]>0; Select[ Range[ 400], k3sQ] (* Harvey P. Dale, May 07 2017 *)

Prog

(PARI) for(n=1, 999, for(k=1, n-1, issquare(n^3-k^3) & !print1(n", ") & break))
(PARI) is(n)=for(k=1, n-1, issquare(n^3-k^3) & return(1))

Crossrefs

Cf. A001922, A038593-A038598, A014439, A014440, A014441, A071954.

Sequence in context: A027693 A196226 A250290 * A100718 A063190 A101763

Adjacent sequences: A228943 A228944 A228945 * A228947 A228948 A228949

Keyword

nonn

Author

M. F. Hasler, Oct 05 2013

Status

approved