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A228627 Primes of the form abcabc..abcab. 4
11311, 11411, 13313, 13513, 13613, 13913, 17117, 17317, 17417, 19219, 19319, 19819, 19919, 21121, 21221, 21521, 21821, 23623, 27127, 27427, 27527, 27827, 29129, 29429, 29629, 31231, 31531, 33533, 37337, 37537, 39139, 39239, 39439, 39839, 41141, 41341, 41641 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The sequence appears to be infinite. The number of terms below 10^1000 is 782.
LINKS
EXAMPLE
a(2)= 11411 is in the sequence because it is a prime of the form abcab.
MATHEMATICA
s[n_]:=Select[Union@Flatten@Table[FromDigits@Flatten@Join[IntegerDigits@Table[b, {n}], {IntegerDigits@Floor[b/10]}], {b, 100, 999}], PrimeQ]; Array[s, 2]//Flatten
Select[FromDigits[Join[#, {#[[1]]}, {#[[2]]}]]&/@Select[Tuples[Range[0, 9], 3], #[[1]]> 0&], PrimeQ] (* Harvey P. Dale, Oct 06 2017 *)
CROSSREFS
Sequence in context: A104017 A317400 A284814 * A178581 A178583 A178589
KEYWORD
nonn,base
AUTHOR
Shyam Sunder Gupta, Aug 28 2013
STATUS
approved

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Last modified May 30 03:30 EDT 2024. Contains 372957 sequences. (Running on oeis4.)