OFFSET
1,5
COMMENTS
The graph makes it apparent that there are fewer primes generated when the prime p increases its length from 3 to 4 and 4 to 5 digits. - T. D. Noe, May 03 2013
LINKS
T. D. Noe, Table of n, a(n) for n = 1..10000
EXAMPLE
a(2)=1 since second prime 3 generates 23. Also a(7)=2 since for the seventh prime 17 we have two primes 317 and 1117.
MATHEMATICA
con[x_, y_] := FromDigits[Join[IntegerDigits[Prime[x]], IntegerDigits[Prime[y]]]]; t={}; Do[c=0; Do[If[PrimeQ[con[i, n]], c=c+1], {i, n}]; AppendTo[t, c], {n, 78}]; t
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jayanta Basu, May 02 2013
STATUS
approved