Primes which contain only one odd digit: Difference between revisions
Primes which contain only one odd digit (view source)
Revision as of 10:36, 27 October 2021
, 2 years agoadd FreeBASIC
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=={{header|FreeBASIC}}==
<lang freebasic>
#include "isprime.bas"
function b(j as uinteger, n as uinteger) as uinteger
'auxiliary function for evendig below
dim as uinteger m = int(log(n-1)/log(5))
return int((n-1-5^m)/5^j)
end function
function evendig(n as uinteger) as uinteger
'produces the integers with only even digits
dim as uinteger m = int(log(n-1)/log(5)), a
a = ((2*b(m, n)) mod 8 + 2)*10^m
if n<=1 or m=0 then return a
for j as uinteger = 0 to m-1
a += ((2*b(j, n)) mod 10)*10^j
next j
return a
end function
dim as uinteger n=1, count = 0, p=1
while p<1000000
p = 1 + evendig(n) 'if it's a prime the odd digit must be the last one
if isprime(p) then
count += 1
if p<1000 then print p
end if
n+=1
wend
print "There are ";count;" such primes below one million."</lang>
=={{header|Go}}==
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