A253910 Concatenation of n-th prime and n-th nonprime.
21, 34, 56, 78, 119, 1310, 1712, 1914, 2315, 2916, 3118, 3720, 4121, 4322, 4724, 5325, 5926, 6127, 6728, 7130, 7332, 7933, 8334, 8935, 9736, 10138, 10339, 10740, 10942, 11344, 12745, 13146, 13748, 13949, 14950, 15151, 15752, 16354, 16755, 17356, 17957, 18158, 19160, 19362, 19763, 19964, 21165, 22366, 22768, 22969
Offset: 1
Examples
a(5) = 119 because the 5th prime is 11 and the 5th nonprime is 9.
Links
- Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Programs
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Haskell
import Data.Function (on) a253911 n = a253911_list !! (n-1) a253911_list = map read $ zipWith ((++) `on` show) a018252_list a000040_list :: [Integer] -- Reinhard Zumkeller, Feb 09 2015
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PARI
nprime(n)=c=0;k=1;while(k,if(!isprime(k),c++);if(c==n,return(k));k++) vector(50,n,eval(concat(Str(prime(n)),Str(nprime(n))))) \\ Derek Orr, Feb 06 2015
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