A102606 Numbers k such that 1kkk1 is prime.

3, 5, 6, 9, 18, 21, 24, 25, 26, 36, 39, 41, 42, 49, 53, 54, 58, 59, 64, 65, 69, 71, 72, 79, 87, 91, 93, 105, 124, 132, 155, 159, 162, 163, 165, 168, 172, 184, 187, 196, 210, 214, 221, 226, 235, 238, 249, 256, 272, 278, 284, 289, 312, 323, 327, 329, 331, 336, 341, 342

Offset

1,1

Links

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Example

If k=3, then 13331 is prime.
If k=39, then 13939391 is prime.
If k=65, then 16565651 is prime.

Mathematica

Select[Range[360], PrimeQ[FromDigits[Flatten[IntegerDigits /@ {1, #, #, #, 1}]]] &]

Crossrefs

Cf. A102607, A102608.

Sequence in context: A176345 A101139 A309140 * A102372 A095829 A054871

Adjacent sequences: A102603 A102604 A102605 * A102607 A102608 A102609

Keyword

nonn,base

Author

Parthasarathy Nambi, Jan 29 2005

Extensions

Extended by Ray Chandler, Jan 30 2005

Status

approved