OFFSET
1,2
LINKS
Eric Weisstein's World of Mathematics, Waring's Problem.
EXAMPLE
a(1) = 1 since 1 = 1^3 (1 way with minimal representation).
a(2) = 157 since 157 = 1^3 + 1^3 + 3^3 + 4^3 + 4^3 = 2^3 + 2^3 + 2^3 + 2^3 + 5^3 (2 ways with minimal representation).
a(3) = 221 since 221 = 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 6^3 = 1^3 + 1^3 + 3^3 + 4^3 + 4^3 + 4^3 = 2^3 + 2^3 + 2^3 + 2^3 + 4^3 + 5^3 (3 ways with minimal representation).
MATHEMATICA
t=Table[r=PowersRepresentations[n, 9, 3]; Sort[Tally[9-Count[#, 0]&/@r]][[1, 2]], {n, 1000}]; u=Union[t]; c=Complement[Range[Max[u]], u]; If[c=={}, mx=u[[-1]], mx=c[[1]]-1]; Flatten[Table[Position[t, n, 1, 1], {n, mx}]]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Martin Renner, Jan 22 2011, Jan 25 2011
EXTENSIONS
a(16)-a(30) from Alois P. Heinz, Feb 10 2011
STATUS
approved