clearvars
digits 1000
idx=combinator(21,2,'c');
n=vpa(2):22;
sf=prod(factorial(n))
n= factorial(n(idx));
for i=1:length(n)
q=sf/prod(n(i,:));
sr=round(sqrt( q));
if sr^2==q
disp(n(i,:))
end
end
The number before division (including all the factorials):
73185187344722251685917129061596359994436879170423331597220791224873045503248922
81148195654813491347532442912806883951929242763804569032720897710945101414400000
0000000000000000000000000000000000000
Pairs of factorial numbers to divide by:
[2, 39916800]
[6, 479001600]
[24, 479001600]
For reference as to which factorials these are:
>> for i=1:13 disp([i,factorial(i)])
end
1 1
2 2
3 6
4 24
5 120
6 720
7 5040
8 40320
9 362880
10 3628800
11 39916800
12 479001600
13 6227020800
indicates factorials (2,11), (3,12) and (4,12) work
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Posted by Charlie
on 2024-11-29 12:53:32 |
computer solution
