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A068697
Smallest prime which is a concatenation of n consecutive odd numbers. If no such prime exists then 0.
1
3, 13, 0, 23252729, 2527293133, 0, 57911131517, 4547495153555759, 0, 135791113151719, 87899193959799101103105107, 0, 23252729313335373941434547, 357911131517192123252729, 0
OFFSET
1,1
COMMENTS
a(3k) = 0.
LINKS
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
Cf. A052077.
Sequence in context: A167368 A318165 A215240 * A010258 A363270 A107774
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Mar 03 2002
EXTENSIONS
More terms from Sascha Kurz, Mar 26 2002
STATUS
approved