Coprime triplets

Find and show the smallest number which is coprime to the last two predecessors and has not yet appeared; a(1)=1, a(2)=2.
p and q are coprimes if they have no common factors other than 1.
Let p, q < 50

Task

FreeBASIC

<lang freebasic>function gcd( a as uinteger, b as uinteger ) as uinteger

   if b = 0 then return a
   return gcd( b, a mod b )

end function

function num_in_array( array() as integer, num as integer ) as boolean

   for i as uinteger = 1 to ubound(array)
       if array(i) = num then return true
   next i
   return false

end function

redim as integer trips(1 to 2) trips(1) = 1 : trips(2) = 2 dim as integer last

do

   last = ubound(trips)
   for q as integer = 1 to 49
       if not num_in_array( trips(), q ) _
         andalso gcd(q, trips(last)) = 1 _
         andalso gcd(q, trips(last-1)) = 1 then
           redim preserve as integer trips( 1 to last+1 )
           trips(last+1) = q
           continue do 
       end if
   next q
   exit do

loop

print using "Found ## terms:"; ubound(trips)

for i as integer = 1 to last

   print trips(i);" ";

next i : print</lang>

Output:

Found 36 terms:
1  2  3  5  4  7  9  8  11  13  6  17  19  10  21  23  16  15  29  14  25  27  22  31  35  12  37  41  18  43  47  20  33  49  26  45

Phix

function coprime_triplets(integer less_than=50)
    sequence cpt = {1,2}
    while true do
        integer m = 1
        while find(m,cpt) 
           or gcd(m,cpt[$])!=1
           or gcd(m,cpt[$-1])!=1 do
            m += 1
        end while
        if m>=less_than then exit end if
        cpt &= m
    end while
    return cpt
end function
sequence res = apply(true,sprintf,{{"%2d"},coprime_triplets()})
printf(1,"Found %d coprime triplets:\n%s\n",{length(res),join_by(res,1,10," ")})

Output:

Found 36 coprime triplets:
 1  2  3  5  4  7  9  8 11 13
 6 17 19 10 21 23 16 15 29 14
25 27 22 31 35 12 37 41 18 43
47 20 33 49 26 45

Ring

<lang ring> see "working..." + nl row = 2 numbers = 1:50 first = 1 second = 2 see "Coprime triplets are:" + nl see "" + first + " " + second + " "

    for n = 3 to len(numbers)
        flag1 = 1
        flag2 = 1
        if first < numbers[n]
           min = first
        else
           min = numbers[n]
        ok
        for m = 2 to min
            if first%m = 0 and numbers[n]%m = 0
               flag1 = 0
               exit
            ok
        next
        if second < numbers[n]
           min = second
        else
           min = numbers[n]
        ok
        for m = 2 to min
            if second%m = 0 and numbers[n]%m = 0 
               flag2 = 0
               exit
            ok
        next
        if flag1 = 1 and flag2 = 1
           see "" + numbers[n] + " "
           first = second 
           second = numbers[n] 
           del(numbers,n)
           row = row+1
           if row%10 = 0
              see nl
           ok
           n = 2
        ok
   next

   see nl + "Found " + row + " coprime triplets" + nl
   see "done..." + nl

</lang>

Output:

working...
Coprime triplets are:
1 2 3 5 4 7 9 8 11 13 
6 17 19 10 21 23 16 15 29 14 
25 27 22 31 35 12 37 41 18 43 
47 20 33 49 26 45 
Found 36 coprime triplets
done...

Wren

Translation of: Phix

Library: Wren-math

Library: Wren-seq

Library: Wren-fmt

<lang ecmascript>import "/math" for Int import "/seq" for Lst import "/fmt" for Fmt

var limit = 50 var cpt = [1, 2]

while (true) {

   var m = 1
   while (cpt.contains(m) || Int.gcd(m, cpt[-1]) != 1 || Int.gcd(m, cpt[-2]) != 1) {
       m = m + 1
   }
   if (m >= limit) break
   cpt.add(m)

} System.print("Coprime triplets under %(limit):") for (chunk in Lst.chunks(cpt, 10)) Fmt.print("$2d", chunk) System.print("\nFound %(cpt.count) such numbers.")</lang>

Output:

Coprime triplets under 50:
 1  2  3  5  4  7  9  8 11 13
 6 17 19 10 21 23 16 15 29 14
25 27 22 31 35 12 37 41 18 43
47 20 33 49 26 45

Found 36 such numbers.