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A179910 Primes with two embedded primes. 2
23, 37, 53, 73, 127, 139, 157, 167, 193, 211, 227, 229, 241, 251, 263, 277, 307, 331, 383, 389, 419, 433, 439, 443, 457, 467, 503, 521, 541, 557, 563, 577, 587, 599, 619, 631, 643, 647, 659, 677, 683, 727, 751, 757, 761, 827, 829, 839, 857, 859, 883, 929 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

It appears that p having n embedded primes means that the set of prime integers generated by contiguous proper substrings of p has size n.

A079066(a(n)) = 2.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

MATHEMATICA

f[n_] := Block[ {id = IntegerDigits@n}, len = Length@ id - 1; Count[ PrimeQ@ Union[ FromDigits@# & /@ Flatten[ Table[ Partition[ id, k, 1], {k, len}], 1]], True] + 1]; Select[ Prime@ Range@ 160, f@# == 3 &]

Select[ Prime@ Range@ 160, Function[ n, Length@ Select[ Union[ FromDigits /@ (Flatten[ Table[ Partition[#, k, 1], {k, Length@ # - 1}], 1] &)@ IntegerDigits@ n], PrimeQ]]@ # == 2 &] (* Michael Somos, Jan 13 2011 *)

PROG

(Haskell)

import Data.List (elemIndices)

a179910 n = a179910_list !! (n-1)

a179910_list = map (a000040 . (+ 1)) $ elemIndices 2 a079066_list

-- Reinhard Zumkeller, Jul 19 2011

CROSSREFS

Cf. A039996, A079397, A033274, A034844, A092621, A179909 - A179919, A033274.

Sequence in context: A190731 A092622 A129351 * A124888 A141521 A080906

Adjacent sequences:  A179907 A179908 A179909 * A179911 A179912 A179913

KEYWORD

base,nonn

AUTHOR

Robert G. Wilson v, Aug 01 2010

STATUS

approved

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Last modified November 20 20:51 EST 2014. Contains 249754 sequences.