A112766 Smallest prime of the form 8 followed by n copies of k.

83, 811, 8111, 839393939, 81313131313, 8212121212121, 83333333, 89191919191919191, 8777777777, 829292929292929292929, 85151515151515151515151, 8313131313131313131313131, 811111111111111111111111111, 81313131313131313131313131313

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..200

Example

a(3) = 8111, 8 followed by three copies of 1.

Mathematica

SelectFirst[#, PrimeQ]&/@Table[FromDigits[PadRight[{8}, IntegerLength[k] n+1, Reverse[IntegerDigits[k]]]], {n, 30}, {k, 9999}] (* Harvey P. Dale, Feb 02 2020 *)

Prog

(PARI) for(n=1, 100, np=1; k=1; while(np, s="8"; for(i=1, n, s=concat(s, Str(k))); m=eval(s); if(isprime(m), print1(m", "); np=0, k++))) - Herman Jamke (hermanjamke(AT)fastmail.fm), May 01 2008

Crossrefs

Sequence in context: A059935 A069596 A290407 * A128950 A068851 A250083

Adjacent sequences: A112763 A112764 A112765 * A112767 A112768 A112769

Keyword

base,nonn,dumb

Author

Amarnath Murthy, Jan 02 2006

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 01 2008

Status

approved