A166572 Prime numbers containing the string 11.

11, 113, 211, 311, 811, 911, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187, 1193, 1511, 1811, 2011, 2111, 2113, 2311, 2411, 2711, 3011, 3119, 3511, 3911, 4111, 4211, 5011, 5113, 5119, 5711, 6011, 6113, 6211, 6311, 6911, 7211, 7411

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

Maple

isA166572 := proc(n) local dgs, wrks; if isprime(n) then dgs := convert(n, base, 10) ; wrks := false; for i from 1 to nops(dgs)-1 do if op(i, dgs) = 1 and op(i+1, dgs) = 1 then return true; end if; od: return false; else false; end if; end proc: for n from 1 to 8000 do if isA166572(n) then printf("%d, ", n) ; end if; od: # R. J. Mathar, Nov 30 2009

Mathematica

p11Q[n_]: = Module[{idn = IntegerDigits[n]}, MemberQ[Partition[idn, 2, 1], {1, 1}]] Select[Prime[Range[1000]], p11Q] (* Vincenzo Librandi, Sep 14 2012 *)
Select[Prime[Range[1000]], SequenceCount[IntegerDigits[#], {1, 1}]>0&] (* Harvey P. Dale, Sep 24 2022 *)

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, 11) \\ Charles R Greathouse IV, Jun 20 2014

Crossrefs

Cf. A166571, A166573, A166579, A166580, A166581, A166582.

Sequence in context: A175684 A090227 A050758 * A111463 A142483 A001268

Adjacent sequences: A166569 A166570 A166571 * A166573 A166574 A166575

Keyword

nonn,base

Author

Vincenzo Librandi, Nov 01 2009

Status

approved