

A038853


Numbers that are divisible by 5 and are the difference between two (different positive) cubes in at least one way.


2



215, 335, 485, 665, 875, 1115, 1330, 1385, 1685, 1720, 2015, 2170, 2375, 2680, 2765, 3185, 3250, 3635, 3880, 4095, 4115, 4570, 4625, 4905, 5165, 5320, 5735, 5805, 6130, 6335, 6795, 6965, 7000, 7625, 7875, 7930, 8315, 8920, 9035, 9045, 9260, 9785, 9970
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..43.


FORMULA

A number is in this sequence iff it is of the form (k+5j)^3k^3, where k,j are any positive integers, since (k+d)^3  k^3 = d(3(k+d/2)^2+d^2/4) = 0 (mod 5) iff d=0 (mod 5), since 3x^2 =y^2/4 (mod 5) iff x=y=0 (mod 5).  M. F. Hasler, Jun 07 2007


PROG

(PARI) A038853(Nmax=10^4, a=[]) = { local(t, j5); for(j=1, Nmax^(1/3)/5, j5=5*j; for(k=1, sqrt((Nmax/j5j5^23*j5)/3), if(Nmax<t=(k+j5)^3k^3, next); a=concat(a, t))); vecsort(a) }  M. F. Hasler, Jun 07 2007


CROSSREFS

Sequence in context: A181008 A191943 A046011 * A038860 A120536 A043391
Adjacent sequences: A038850 A038851 A038852 * A038854 A038855 A038856


KEYWORD

nonn


AUTHOR

Jeff Burch


EXTENSIONS

Corrected by M. F. Hasler, Jun 07 2007


STATUS

approved



