A243529 Prime numbers containing the string 12.

127, 1123, 1129, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, 1297, 2129, 3121, 4127, 4129, 6121, 7121, 7127, 7129, 8123, 9127, 11213, 11239, 11243, 11251, 11257, 11261, 11273, 11279, 11287

Offset: 1

Author

Vincenzo Librandi, Jun 06 2014

Keywords

• nonn
• base
• less

Comments

Subsequence of A208272. [Bruno Berselli, May 06 2015]

Links

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

Crossrefs

Cf. similar sequences listed in A257667.

Programs

Mathematica

Select[Prime[Range[2000]], ! StringFreeQ[ToString[#], "12" ] &]

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

Formula

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