A068815 Primes with a 4 followed by 1's.

41, 4111, 41111111111111, 41111111111111111111111111, 4111111111111111111111111111111111111111111111111111111111111111111111111

Offset

1,1

Comments

The next term a(6) has 109 digits and is too large to be displayed here.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..10

Makoto Kamada, Prime numbers of the form 411...11.

Index entries for primes involving repunits

Mathematica

Select[Table[FromDigits[PadRight[{4}, n, 1]], {n, 1000}], PrimeQ] (* Harvey P. Dale, Sep 15 2019 *)

Prog

(PARI) for(n=1, 200, if(isprime(4*10^n+(10^(n)-1)/9)==1, print1(4*10^n+(10^(n)-1)/9, ", ")))

Crossrefs

Cf. A002275, A056706 (corresponding values of n).

Sequence in context: A233015 A282054 A107690 * A093174 A280677 A209104

Adjacent sequences: A068812 A068813 A068814 * A068816 A068817 A068818

Keyword

nonn,base

Author

Amarnath Murthy, Mar 07 2002

Extensions

More terms from Benoit Cloitre, Mar 09 2002

Status

approved