OFFSET
1,27
COMMENTS
By Lagrange's four square theorem, the minimal number of squares required to represent a number is 4 or less. See A141490 for the numbers k that have n minimal representations.
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
EXAMPLE
27 has the following representations as the sum of 4 or fewer squares: 1+1+25, 9+9+9, and 1+1+9+16. The minimal number of squares is 3 and there are 2 such representations. Hence a(27)=2.
MATHEMATICA
Table[r=PowersRepresentations[n, 4, 2]; Sort[Tally[4-Count[#, 0]& /@ r]][[1, 2]], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Jan 19 2011
STATUS
approved