Chowla numbers: Difference between revisions
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33,550,336 is a perfect number.
</pre>
=={{header|Ruby}}==
{{trans|C}}
<lang ruby>def chowla(n)
sum = 0
i = 2
while i * i <= n do
if n % i == 0 then
sum = sum + i
j = n / i
if i != j then
sum = sum + j
end
end
i = i + 1
end
return sum
end
def main
for n in 1 .. 37 do
puts "chowla(%d) = %d" % [n, chowla(n)]
end
count = 0
power = 100
for n in 2 .. 10000000 do
if chowla(n) == 0 then
count = count + 1
end
if n % power == 0 then
puts "There are %d primes < %d" % [count, power]
power = power * 10
end
end
count = 0
limit = 350000000
k = 2
kk = 3
loop do
p = k * kk
if p > limit then
break
end
if chowla(p) == p - 1 then
puts "%d is a perfect number" % [p]
count = count + 1
end
k = kk + 1
kk = kk + k
end
puts "There are %d perfect numbers < %d" % [count, limit]
end
main()</lang>
{{out}}
<pre>chowla(1) = 0
chowla(2) = 0
chowla(3) = 0
chowla(4) = 2
chowla(5) = 0
chowla(6) = 5
chowla(7) = 0
chowla(8) = 6
chowla(9) = 3
chowla(10) = 7
chowla(11) = 0
chowla(12) = 15
chowla(13) = 0
chowla(14) = 9
chowla(15) = 8
chowla(16) = 14
chowla(17) = 0
chowla(18) = 20
chowla(19) = 0
chowla(20) = 21
chowla(21) = 10
chowla(22) = 13
chowla(23) = 0
chowla(24) = 35
chowla(25) = 5
chowla(26) = 15
chowla(27) = 12
chowla(28) = 27
chowla(29) = 0
chowla(30) = 41
chowla(31) = 0
chowla(32) = 30
chowla(33) = 14
chowla(34) = 19
chowla(35) = 12
chowla(36) = 54
chowla(37) = 0
There are 25 primes < 100
There are 168 primes < 1000
There are 1229 primes < 10000
There are 9592 primes < 100000
There are 78498 primes < 1000000
There are 664579 primes < 10000000
6 is a perfect number
28 is a perfect number
496 is a perfect number
8128 is a perfect number
33550336 is a perfect number
There are 5 perfect numbers < 350000000</pre>
=={{header|Scala}}==
Line 3,165 ⟶ 3,271:
4: 8,128
5: 33,550,336</pre>
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=={{header|Swift}}==
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