Quadrat special primes: Difference between revisions

=={{header|Nim}}==

<lang Nim>import math, strutils, sugar

func isPrime(n: Natural): bool =

if n < 2: return false

if n mod 2 == 0: return n == 2

if n mod 3 == 0: return n == 3

var d = 5

while d * d <= n:

if n mod d == 0: return false

inc d, 2

if n mod d == 0: return false

inc d, 4

result = true

const

Max = 16_000

Squares = collect(newSeq):

for n in countup(2, sqrt(Max.float).int, 2): n * n

iterator quadraPrimes(lim: Positive): int =

assert lim >= 3

yield 2

yield 3

var n = 3

block mainloop:

while true:

for square in Squares:

let next = n + square

if next > lim: break mainloop

if next.isPrime:

n = next

yield n

break

echo "Quadrat special primes < 16000:"

var count = 0

for qp in quadraPrimes(Max):

inc count

stdout.write ($qp).align(5), if count mod 7 == 0: '\n' else: ' '</lang>

{{out}}

<pre>Quadrat special primes < 16000:

2 3 7 11 47 83 227

263 587 911 947 983 1019 1163

1307 1451 1487 1523 1559 2459 3359

4259 4583 5483 5519 5843 5879 6203

6779 7103 7247 7283 7607 7643 8219

8363 10667 11243 11279 11423 12323 12647

12791 13367 13691 14591 14627 14771 15671</pre>