A102619 Numbers which are the sum of two positive cubes and divisible by 19.

133, 152, 513, 855, 1064, 1216, 1729, 1843, 2071, 2261, 2413, 2869, 2926, 3059, 3439, 3591, 4104, 4123, 4921, 4940, 5833, 6175, 6840, 7163, 7657, 8512, 9386, 9728, 10773, 13167, 13357, 13718, 13832, 13851, 14174, 14364, 14744, 15542, 15561, 16568

Offset

1,1

Comments

If 12*h-1083 is a square then some values of 19*h are in this sequence. It is easy to verify that h is of the form 3*m^2-3*m+91, and therefore 19*(3*m^2-3*m+91) = (10-m)^3+(m+9)^3. - Vincenzo Librandi, May 10 2013

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, 19] == 0, Sow@t], {x, n^(1/3)}, {y, Min[x, (n - x^3)^(1/3)]}]][[2, 1]]]; upto[17000] (* Giovanni Resta, Jun 12 2020 *)

Prog

(Magma) [n: n in [2..2*10^4] | exists{i: i in [1..Iroot(n-1, 3)] | IsPower(n-i^3, 3) and IsZero(n mod 19)}]; // Bruno Berselli, May 10 2013

Crossrefs

Cf. A003325, A101421 (divisible by k=7), A101852 (k=11), A094447 (k=13), A099178 (k=17), A101806 (k=23), A224483 (k=29), A102658 (k=31), A102618 (k=37).

Sequence in context: A003915 A046439 A031188 * A020446 A123997 A316630

Adjacent sequences: A102616 A102617 A102618 * A102620 A102621 A102622

Keyword

nonn,easy

Author

Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Jan 31 2005

Status

approved