Strange numbers

Strange numbers is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

n is a strange number if every adjacent digit differs from its neighbour by prime number.
Let 100<n<500

Pascal

simple brute force, by adding a prime difference from digit to digit. <lang pascal>program strangenumbers; type

 tDeltaIdx = 0..7;

const

 dgtCnt = 3;
 deltaprime : array[tDeltaIdx] of Int32 =(-7,-5,-3,-2,2,3,5,7);

//globals are set to 0 var

 Digits : array[0..dgtCnt-1] of Int32;
 Actdgt,i,j,k,Cnt : Int32;  

procedure OutPut; Begin

 write(Digits[0],Digits[1],Digits[2],' ');

end;

Begin

 For i := 1 to 4 do
 Begin
   Digits[0] := i;
   For k in tDeltaIdx do
   Begin
     if (i+deltaprime[k]) in [0..9] then
     Begin
       Actdgt := i+deltaprime[k];
       Digits[1]:= Actdgt;      
       For j in tDeltaIdx do
         if (Actdgt+deltaprime[j]) in [0..9] then
         Begin
           Digits[2]:= Actdgt+deltaprime[j];
           OutPut;
           inc(cnt);
           If cnt MOD 20 = 0 then 
             writeln;
         end;
       end;
     end;
   end;  
 writeln;  
 Writeln('Count : ',cnt);

end. </lang>

Output:

130 131 135 136 138 141 142 146 147 149 161 163 164 168 169 181 183 185 186 202 
203 205 207 241 242 246 247 249 250 252 253 257 258 270 272 274 275 279 292 294 
296 297 302 303 305 307 313 314 316 318 350 352 353 357 358 361 363 364 368 369 
381 383 385 386 413 414 416 418 420 424 425 427 429 461 463 464 468 469 470 472 
474 475 479 492 494 496 497 
Count : 87

Raku

<lang perl6># 20210222 Raku programming solution

sub infix:<′>(\x,\y) { abs(x -y) ∈ [2, 3, 5, 7] ?? True !! False }

for (101..499) { .say if so all .comb.rotor(2 => -1).map: { @_[0] ′ @_[1] } }</lang>

Output:

./strange.raku   | wc
87      87     348

Ring

<lang ring> load "stdlib.ring"

row = 0 see "Strange numbers are:"

for n = 100 to 500

   flag = 1
   str = string(n)
   for m = 1 to len(str)-1
       num1 = number(str[m])
       num2 = number(str[m+1])
       pr = fabs(num1-num2)
       if not isprime(pr)
          flag = 0
          exit
       ok
    next
    if flag = 1
       row = row + 1
       if (row-1) % 11 = 0
          see nl
       else
          see " " + str
       ok
    ok

next </lang>

Output:

Strange numbers are:
 131 135 136 138 141 142 146 147 149 161
 164 168 169 181 183 185 186 202 203 205
 241 242 246 247 249 250 252 253 257 258
 272 274 275 279 292 294 296 297 302 303
 307 313 314 316 318 350 352 353 357 358
 363 364 368 369 381 383 385 386 413 414
 418 420 424 425 427 429 461 463 464 468
 470 472 474 475 479 492 494 496 497

Wren

<lang ecmascript>var primes = [2, 3, 5, 7] var count = 0 var d = [] System.print("Strange numbers in the open interval (100, 500) are:\n") for (i in 101..499) {

   d.clear()
   var j = i
   while (j > 0) {
      d.add(j % 10)
      j = (j/10).floor
   }
   if (primes.contains((d[0] - d[1]).abs) && primes.contains((d[1] - d[2]).abs)) {
       System.write("%(i) ")
       count = count + 1
       if (count % 10 == 0) System.print()
   }

} if (count % 10 != 0) System.print() System.print("\n%(count) strange numbers in all.")</lang>

Output:

Strange numbers in the open interval (100, 500) are:

130 131 135 136 138 141 142 146 147 149 
161 163 164 168 169 181 183 185 186 202 
203 205 207 241 242 246 247 249 250 252 
253 257 258 270 272 274 275 279 292 294 
296 297 302 303 305 307 313 314 316 318 
350 352 353 357 358 361 363 364 368 369 
381 383 385 386 413 414 416 418 420 424 
425 427 429 461 463 464 468 469 470 472 
474 475 479 492 494 496 497 

87 strange numbers in all.