The number N is a sum of 4 different numbers, each being a square of one of the 4 smallest divisors of N (e.g. N=36 does not qualify since 1^2+2^2+3^2+4^2
sums up to 30, not 36.)
Provide a full list of
similar numbers or show that none exist.
Two software notes:
Here is the Gnu Fortran version of the same routine for comparison.
Also, I worry about Charlie's cutoff of "sr=sqr(N)"
This would have missed, e.g., 3 as a factor of 6 (I think).
(I note this because I did the same thing at first.)
(Later... thinking it over, this makes sense since we can't use factors greater than sqrt(N) for the sum. Never mind!)
program dd
implicit none
integer list(4),i,j,k,jj,cnt
do 1 i=1,100000
cnt=0
do k=1,i
if(k*int((1.*i)/k).eq.i)then
cnt=cnt+1
list(cnt)=k
if(cnt.eq.4)then
jj=list(1)**2+list(2)**2+list(3)**2+list(4)**2
if(jj.eq.i)then
print*,' solved: ',i,list
go to 1
else
go to 1
endif
endif
endif
enddo
1 enddo
end
rabbit-3:~ lord$ dd
solved: 130 1 2 5 10
Edited on July 9, 2018, 2:49 am
Edited on July 9, 2018, 6:21 pm
Just S/W notes...
