Factorial primes: Difference between revisions
Added Lua
(→{{header|ALGOL 68}}: Simplified also make it more DRY and less WET) |
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9: 12! - 1 = 479001599
10: 14! - 1 = 87178291199
</pre>
=={{header|Lua}}==
{{Trans|ALGOL 68}}
<syntaxhighlight lang="lua">
do -- find some factorial primes - primes that are f - 1 or f + 1
-- for some factorial f
function isPrime( p )
if p <= 1 or p % 2 == 0 then
return p == 2
else
local prime = true
local i = 3
local rootP = math.floor( math.sqrt( p ) )
while i <= rootP and prime do
prime = p % i ~= 0
i = i + 1
end
return prime
end
end
local f = 1
local fpCount = 0
local n = 0
local fpOp = ""
while fpCount < 10 do
n = n + 1
f = f * n
fpOp = "-"
for fp = f - 1, f + 1, 2 do
if isPrime( fp ) then
fpCount = fpCount + 1
io.write( string.format( "%2d", fpCount ), ":"
, string.format( "%4d", n ), "! "
, fpOp, " 1 = ", fp, "\n"
)
end
fpOp = "+"
end
end
end
</syntaxhighlight>
{{out}}
<pre>
1: 1! + 1 = 2
2: 2! + 1 = 3
3: 3! - 1 = 5
4: 3! + 1 = 7
5: 4! - 1 = 23
6: 6! - 1 = 719
7: 7! - 1 = 5039
8: 11! + 1 = 39916801
9: 12! - 1 = 479001599
10: 14! - 1 = 87178291199
</pre>
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