A243527 Prime numbers containing the string 111.

1117, 2111, 4111, 8111, 10111, 11113, 11117, 11119, 11131, 11149, 11159, 11161, 11171, 11173, 11177, 11197, 16111, 22111, 25111, 26111, 28111, 35111, 40111, 41113, 41117, 44111, 47111, 50111, 58111, 65111, 68111, 70111, 71119, 79111, 80111

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

Select[Prime[Range[90000]], !StringFreeQ[ToString[#], "111"]&]

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

Crossrefs

Cf. prime numbers containing the string kkk: this sequence (k=1), A166580 (k=2), A166581 (k=3), A166582 (k=4), A167281 (k=5), A131645 (k=6), A167282 (k=7), A167290 (k=8), A167292 (k=9).

Sequence in context: A221428 A161848 A020380 * A251360 A201034 A264312

Adjacent sequences: A243524 A243525 A243526 * A243528 A243529 A243530

Keyword

nonn,base,easy

Author

Vincenzo Librandi, Jun 06 2014

Status

approved