OFFSET
1,2
COMMENTS
This sequence is not monotonically increasing: a(21)=33230 > a(26)=29563.
LINKS
Eric Weisstein's World of Mathematics, Waring's Problem.
EXAMPLE
a(1) = 1 since 1 = 1^4 (1 way with minimal representation)
a(2) = 259 since 259 = 1^4 + 1^4 + 1^4 + 4^4 = 2^4 + 3^4 + 3^4 + 3^4 (2 ways with minimal representation)
a(3) = 518 since 518 = 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 4^4 + 4^4 = 1^4 + 1^4 + 1^4 + 2^4 + 3^4 + 3^4 + 3^4 + 4^4 = 2^4 + 2^4 + 3^4 + 3^4 + 3^4 + 3^4 + 3^4 + 3^4 (3 ways with minimal representation)
MATHEMATICA
t=Table[r=PowersRepresentations[n, 19, 4]; Sort[Tally[19-Count[#, 0]&/@r]][[1, 2]], {n, 800}]; 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
AUTHOR
Martin Renner, Feb 09 2011
EXTENSIONS
a(10)-a(36) from Alois P. Heinz, Feb 10 2011
STATUS
approved