A274384 - OEIS

%I #11 Jun 27 2016 07:55:02

%S 1,2,4,5,7,8,10,11,13,14,16,17,19,20,22,23,25,26,28,29,31,32,34,37,40,

%T 43,46

%N Numbers n such that 2^n is not the average of three positive cubes.

%C Numbers n such that 3*2^n = x^3 + y^3 + z^3 where x, y, z > 0, is not soluble.

%C Numbers n such that A007283(n) is not the sum of three positive cubes.

%C Sequence is finite because 47, 48, and 49 are not in the sequence and the absence of k from the sequence implies the absence of k+3. - _Giovanni Resta_, Jun 27 2016

%e 47 is not a term because 2^47 = (8288^3 + 49808^3 + 66800^3) / 3.

%e 49 is not a term because 2^49 = (13379^3 + 70082^3 + 110309^3) / 3.

%Y Cf. A000079, A003072, A007283.

%K nonn,fini,full

%O 1,2

%A _Altug Alkan_, Jun 19 2016