OFFSET
1,1
COMMENTS
a(3k) = 0.
LINKS
Sean A. Irvine, Table of n, a(n) for n = 1..100
EXAMPLE
a(4) = 23252729 as a concatenation of 23,25,27 and 29. a(3) = 0 for a concatenation of 3 odd numbers is always a multiple of 3.
MATHEMATICA
d[n_]:=IntegerDigits[n]; t={3}; Do[If[Mod[m, 3]==0, x=0, k=1; While[!PrimeQ[x=FromDigits[Fold[Join, d[k], Table[d[k+2n], {n, m-1}]]]], k++]]; AppendTo[t, x], {m, 2, 15}]; t (* Jayanta Basu, May 21 2013 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Mar 03 2002
EXTENSIONS
More terms from Sascha Kurz, Mar 26 2002
STATUS
approved