One-two primes: Difference between revisions

=={{header|Wren}}==

{{libheader|Wren-gmp}}

{{libheader|Wren-fmt}}

{{libheader|Wren-iterate}}

This is based on the Python code in the OEIS entry. Run time about 52 seconds.

<syntaxhighlight lang="ecmascript">import "./gmp" for Mpz

import "./fmt" for Fmt

import "./iterate" for Stepped

var firstOneTwo = Fn.new { |n|

var k = Mpz.ten.pow(n).sub(Mpz.one).div(Mpz.nine)

var r = Mpz.one.lsh(n).sub(Mpz.one)

var m = Mpz.zero

while (m <= r) {

var t = k + Mpz.fromStr(m.toString(2))

if (t.probPrime(15) > 0) return t

m.inc

}

return Mpz.minusOne

}

for (n in 1..20) Fmt.print("$4d: $i", n, firstOneTwo.call(n))

for (n in Stepped.new(100..2000, 100)) {

var t = firstOneTwo.call(n)

if (t == Mpz.minusOne) {

System.print("No %(n)-digit prime found with only digits 1 or 2.")

} else {

var ts = t.toString

var ix = ts.indexOf("2")

Fmt.print("$4d: (1 x $4d) $s", n, ix, ts[ix..-1])

}

}</syntaxhighlight>

{{out}}

<pre>

1: 2

2: 11

3: 211

4: 2111

5: 12211

6: 111121

7: 1111211

8: 11221211

9: 111112121

10: 1111111121

11: 11111121121

12: 111111211111

13: 1111111121221

14: 11111111112221

15: 111111112111121

16: 1111111112122111

17: 11111111111112121

18: 111111111111112111

19: 1111111111111111111

20: 11111111111111212121

100: (1 x 92) 21112211

200: (1 x 192) 21112211

300: (1 x 288) 211121112221

400: (1 x 390) 2111122121

500: (1 x 488) 221222111111

600: (1 x 590) 2112222221

700: (1 x 689) 21111111111

800: (1 x 787) 2122222221111

900: (1 x 891) 222221221

1000: (1 x 988) 222122111121

1100: (1 x 1087) 2112111121111

1200: (1 x 1191) 211222211

1300: (1 x 1289) 22121221121

1400: (1 x 1388) 222211222121

1500: (1 x 1489) 21112121121

1600: (1 x 1587) 2121222122111

1700: (1 x 1688) 212121211121

1800: (1 x 1791) 221211121

1900: (1 x 1889) 22212212211

2000: (1 x 1989) 22121121211

</pre>