A050758 Primes containing at least one pair of consecutive equal digits.

11, 113, 199, 211, 223, 227, 229, 233, 277, 311, 331, 337, 433, 443, 449, 499, 557, 577, 599, 661, 677, 733, 773, 811, 877, 881, 883, 887, 911, 977, 991, 997, 1009, 1033, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187, 1193, 1223, 1229

Offset: 1

Author

Patrick De Geest, Sep 15 1999

Keywords

• nonn
• base

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A043096, A000040, A050757, A029743.

Programs

Mathematica

Select[Prime[Range[205]],MemberQ[Differences[IntegerDigits[#]],0]&] (* Jayanta Basu, May 31 2013 *)
Select[Prime[Range[300]],SequenceCount[IntegerDigits[#],{x_,x_}]>0&] (* The program uses the SequenceCount function from Mathematica version 10 *) (* Harvey P. Dale, Feb 20 2016 *)

PARI

is(n)=my(d=digits(n)); for(i=2,#d,if(d[i]==d[i-1], return(isprime(n)))); 0 \\ Charles R Greathouse IV, Aug 29 2015

Formula

a(n) ~ n log n. - Charles R Greathouse IV, Aug 29 2015