A175684 a(0)=11, then a(n) is the smallest prime p not already used such that (first two digits of p) = (last two digits of a(n-1)).

11, 113, 13, 131, 31, 311, 1117, 17, 173, 73, 733, 331, 313, 137, 37, 373, 739, 397, 97, 971, 71, 719, 19, 191, 911, 1123, 23, 233, 337, 379, 79, 797, 977, 773, 7321, 211, 1129, 29, 293, 937, 3719, 193, 9311, 1151, 5113, 139, 3911, 1153, 53, 5323, 239, 3917, 179

Offset

0,1

Comments

The next-to-last digit of p is not allowed to be zero.

E.g., after a(5)=311, we don't take 1103 and 1109 but 1117.

Links

Zak Seidov, Table of n, a(n) for n = 0..1000

Mathematica

s={11}; id2={1, 1}; Do[Do[p=Prime[k]; If[FreeQ[s, p], idp=IntegerDigits[p]; If[id2==Take[idp, 2]&&idp[[ -2]]>0, AppendTo[s, p]; id2=Take[idp, -2]; Break[]]], {k, 6, 10^7}], {1000}]; s

Crossrefs

Sequence in context: A053055 A024148 A323477 * A090227 A050758 A166572

Adjacent sequences: A175681 A175682 A175683 * A175685 A175686 A175687

Keyword

base,nonn

Author

Zak Seidov, Aug 09 2010

Status

approved