The sieve of Sundaram: Difference between revisions
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1 millionth Prime Found: 15485867
</pre>
=={{header|FreeBASIC}}==
<syntaxhighlight lang="vbnet">Function sieve_of_Sundaram(n As Uinteger) As Uinteger Ptr
If n < 3 Then Return 0
Dim As Uinteger r = Cint(Sqr(n))
Dim As Uinteger k = Cint((n - 3) / 2) + 1
Dim As Uinteger l = Cint((r - 3) / 2) + 1
Dim As Uinteger Ptr primes = Callocate(k, Sizeof(Uinteger))
Dim As Boolean Ptr marked = Callocate(k, Sizeof(Boolean))
For i As Uinteger = 1 To l
Dim As Uinteger p = 2 * i + 1
Dim As Uinteger s = Cint((p * p - 1) / 2)
For j As Uinteger = s To k Step p
marked[j] = True
Next j
Next i
Dim As Uinteger count = 0
For i As Uinteger = 1 To k
If Not marked[i] Then
primes[count] = 2 * i + 1
count += 1
End If
Next i
Return primes
End Function
Const limit As Uinteger = 16e6
Dim As Uinteger Ptr s = sieve_of_Sundaram(limit)
Print "First 100 odd primes generated by the Sieve of Sundaram:"
For i As Uinteger = 0 To 99
Print Using "#####"; s[i];
If (i + 1) Mod 10 = 0 Then Print
Next i
Print !"\nSundaram primes start with 3."
Print !"\nThe 100th Sundaram prime is: "; s[99]
Print !"\nThe 1000000th Sundaram prime is: "; s[999999]
Sleep</syntaxhighlight>
{{out}}
<pre>First 100 odd primes generated by the Sieve of Sundaram:
3 5 7 11 13 17 19 23 29 31
37 41 43 47 53 59 61 67 71 73
79 83 89 97 101 103 107 109 113 127
131 137 139 149 151 157 163 167 173 179
181 191 193 197 199 211 223 227 229 233
239 241 251 257 263 269 271 277 281 283
293 307 311 313 317 331 337 347 349 353
359 367 373 379 383 389 397 401 409 419
421 431 433 439 443 449 457 461 463 467
479 487 491 499 503 509 521 523 541 547
Sundaram primes start with 3.
The 100th Sundaram prime is: 547
The 1000000th Sundaram prime is: 15485867</pre>
=={{header|Go}}==
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