OFFSET
1,1
COMMENTS
Let S = {h^6, h >=1} and T = {32*k^6, k >=1}. Then S and T are disjoint. The position of n^6 in the ordered union of S and T is A249117(n), and the position of 32*n^6 is A249118(n). Equivalently, the latter two give the positions of n*2^(2/3) and n*2^(3/2), respectively, when all the numbers h*2^(2/3) and k*2^(3/2) are jointly ranked.
EXAMPLE
{h^6, h >=1} = {1, 64, 729, 4096, 15625, 46656, 117649, ...};
{32*k^6, k >=1} = {32, 2048, 23328, 131072, 500000, ...};
so the ordered union is {1, 32, 64, 729, 2048, 4096, 15625, ...}, and a(2) = 5
because 32*2^6 is in position 5 of the ordered union.
MATHEMATICA
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Oct 21 2014
STATUS
approved