OFFSET
1,1
LINKS
FORMULA
{n: A025428(n) >= 7}. - R. J. Mathar, Jun 15 2018
MAPLE
N:= 1000: # for terms <= N
B:= Vector(N):
for i from 1 while 4*i^2 <= N do
for j from i while i^2 + 3*j^2 <= N do
for k from j while i^2 + j^2 + 2*k^2 <= N do
for l from k do
m:= i^2 + j^2 + k^2 + l^2;
if m > N then break fi;
B[m]:= B[m]+1
od od od od:
select(t -> B[t] >= 7, [$1..N]); # Robert Israel, Oct 23 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved