A089777 a(n) = smallest prime of the form n followed by a prime.
13, 23, 37, 43, 53, 67, 73, 83, 97, 103, 113, 127, 137, 1423, 157, 163, 173, 1811, 193, 2011, 2111, 223, 233, 2411, 257, 263, 277, 283, 293, 307, 313, 3217, 337, 347, 353, 367, 373, 383, 397, 4013, 4111, 4211, 433, 443, 457, 463, 4723, 487, 4919, 503, 5113
Offset: 1
Links
- T. D. Noe, Table of n, a(n) for n=1..10000
Crossrefs
Cf. A096915 (gives the primes that are appended to n). - R. J. Mathar, Jan 05 2009
Programs
-
Maple
cat2 := proc(a,b) local dgs ; dgs := max(1,ilog10(b)+1) ; a*10^dgs+b ; end: A089777 := proc(k) local i,p,q ; for i from 1 do p := ithprime(i) ; q := cat2(k,p) ; if isprime(q) then RETURN(q) ; fi; od: end: for k from 1 to 80 do printf("%d,",A089777(k)) ; od: # R. J. Mathar, Jan 05 2009
-
Mathematica
Table[k=2; While[p=FromDigits[Join[IntegerDigits[n],IntegerDigits[Prime[k]]]]; !PrimeQ[p], k++ ]; p, {n,100}] (* T. D. Noe, Jan 06 2009 *)
Extensions
Extended by T. D. Noe and R. J. Mathar, Jan 06 2009
Comments