OFFSET
1,1
COMMENTS
Open problem(?): show that a(n) always exists.
LINKS
T. D. Noe, Table of n, a(n) for n=1..10000
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 *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Nov 24 2003
EXTENSIONS
Extended by T. D. Noe and R. J. Mathar, Jan 06 2009
STATUS
approved