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A180679 Numbers with three distinct prime factors which when concatenated in any order form prime numbers. 4
3311, 27181, 32153, 41237, 53977, 86507, 110971, 125069, 208579, 256413, 500981, 543337, 853811, 901949, 964481, 1053787, 1144171, 1197851, 1215731, 1344539, 1385189, 1433659, 1549603, 1674741, 1681547, 1699481, 1973479, 2028181 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence admits only numbers with three distinct prime factors. A denser sequence (a superset) is obtained if prime factors may be repeated. [From R. J. Mathar, Oct 03 2010]

There is no term with four distinct prime factors under 10^8. [From Dmitri Kamenetsky, Sep 29 2012]

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

For 3311, 3311=7 * 11 * 43, and 71143, 74311, 43711, 43117, 11437, 11743 are all prime numbers.

MATHEMATICA

Take[Union[Times @@@ Select[Subsets[Prime[Range[300]], {3}], And @@ PrimeQ[FromDigits /@ (Flatten /@ (IntegerDigits /@ Permutations[#]))] &]], 30] (* Harvey P. Dale, Jan 29 2011 *)

CROSSREFS

Cf. A181559, A217263, A217264, A217265.

Sequence in context: A106724 A239671 A181559 * A251900 A078348 A078963

Adjacent sequences:  A180676 A180677 A180678 * A180680 A180681 A180682

KEYWORD

nonn,base

AUTHOR

James Farrington, Sep 15 2010

EXTENSIONS

Missing values inserted by R. J. Mathar, Oct 03 2010

STATUS

approved

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Last modified April 11 15:49 EDT 2021. Contains 342886 sequences. (Running on oeis4.)