A110781 Number of digits in A110780(n).

2, 5, 9, 10, 38, 47, 1279, 11389

Offset: 1

Author

Amarnath Murthy, Aug 12 2005

Keywords

• base
• nonn
• more

Comments

a(8) > 8000. - Michael S. Branicky, Aug 24 2022

Crossrefs

Cf. A110774, A110775, A110776, A110777, A110778, A110780.

Programs

Python

from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
    s = ""
    while True:
        for d in "19":
            for k in count(1):
                if isprime(int(s+d*k)): break
            yield k
            s += d*k
print(list(islice(agen(), 7))) # Michael S. Branicky, Aug 24 2022

Extensions

More terms from Joshua Zucker, Jan 11 2006

a(7) from Sean A. Irvine, Mar 22 2010

a(8) from Michael S. Branicky, Jun 24 2023