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A102606
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Numbers n such that 1nnn1 is prime.
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2
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| If n=3, then 13331 is prime.
If n=39, then 13939391 is prime.
If n=65, then 16565651 is prime.
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MATHEMATICA
| Select[Range[360], PrimeQ[FromDigits[Flatten[IntegerDigits /@ {1, #, #, #, 1}]]] &]
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CROSSREFS
| Cf. A102607, A102608.
Sequence in context: A070117 A176345 A101139 * A102372 A095829 A182637
Adjacent sequences: A102603 A102604 A102605 * A102607 A102608 A102609
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KEYWORD
| nonn,base
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Jan 29 2005
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 30 2005
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