A166580 - OEIS

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A166580

Prime numbers containing the string 222.

2221, 12227, 22229, 22247, 22259, 22271, 22273, 22277, 22279, 22283, 22291, 42221, 42223, 42227, 52223, 72221, 72223, 72227, 72229, 82223, 92221, 92227, 102229, 112223, 122201, 122203, 122207, 122209, 122219, 122231, 122251, 122263, 122267

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OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

a(n) ~ n log n. - Charles R Greathouse IV, Jun 20 2014

MATHEMATICA

p222Q[n_] := Module[{idn = IntegerDigits[n]}, MemberQ[Partition[idn, 3, 1], {2, 2, 2}]]; Select[Prime[Range[15000]], p222Q] (* Vincenzo Librandi Sep 14 2012 *)

Select[Prime[Range[12000]], SequenceCount[IntegerDigits[#], {2, 2, 2}]>0&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 08 2017 *)

PROG

(PARI) contains(n, k)=my(N=digits(n), K=digits(k)); for(i=0, #N-#K, for(j=1, #K, if(N[i+j]!=K[j], next(2))); return(1)); 0

is(n)=isprime(n) && contains(n, 222) \\ Charles R Greathouse IV, Jun 20 2014

CROSSREFS

Cf. A166571 - A166573, A166579, A166581, A166582.

Sequence in context: A092992 A210712 A260175 * A091189 A046443 A257826

Adjacent sequences: A166577 A166578 A166579 * A166581 A166582 A166583

KEYWORD

nonn,base

AUTHOR

Vincenzo Librandi, Nov 01 2009

STATUS

approved