A224485 Numbers which are the sum of two positive cubes and divisible by 5.

35, 65, 250, 280, 370, 520, 730, 855, 945, 1125, 1395, 1755, 2000, 2060, 2205, 2240, 2540, 2745, 2960, 3500, 3925, 4075, 4160, 4375, 4825, 4940, 5425, 5840, 6175, 6750, 6840, 6860, 7075, 7110, 7560, 8125, 8190, 9000, 9325, 9990

Offset

1,1

Comments

If 12*h-75 is a square then some values of 5*h are in this sequence. It is easy to verify that h is of the form 3*m^2-3*m+7, and therefore 5*(3*m^2-3*m+7) = (3-m)^3+(m+2)^3.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Mathematica

upto[n_] := Block[{t}, Union@ Reap[ Do[If[Mod[t = x^3 + y^3, 5] == 0, Sow@t], {x, n^(1/3)}, {y, Min[x, (n - x^3)^(1/3)]}]][[2, 1]]]; upto[10000] (* Giovanni Resta, Jun 12 2020 *)

Crossrefs

Cf. A224484 (divisible by k=3), A101421 (k=7), A101852 (k=11), A094447 (k=13), A099178 (k=17), A102619 (k=19), A101806 (k=23), A224483 (k=29), A102658 (k=31), A102618 (k=37).

Sequence in context: A297150 A292081 A162832 * A267330 A353175 A229357

Adjacent sequences: A224482 A224483 A224484 * A224486 A224487 A224488

Keyword

nonn,easy

Author

Vincenzo Librandi, May 10 2013

Status

approved