A110777 Number of digits in A110776(n).

2, 3, 2, 6, 9, 25, 9, 3, 762, 354, 248, 2181, 606, 1941, 6423, 11871

Offset: 1

Author

Amarnath Murthy, Aug 12 2005

Keywords

• base
• nonn
• more

Crossrefs

Cf. A110774, A110775, A110776, A110778, A112534, A110780, A110781, A110782, A110783, A110788, A110789

Programs

Python

from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
    s = ""
    while True:
        for d in "17":
            for k in count(1):
                if isprime(int(s+d*k)): break
            yield k
            s += d*k
print(list(islice(agen(), 11))) # Michael S. Branicky, Aug 23 2022

Extensions

a(7)-a(9) from Joshua Zucker, Jan 11 2006

a(10)-a(11) from Sean A. Irvine, Mar 22 2010

a(12)-a(14) from Michael S. Branicky, Aug 23 2022

a(15) from Michael S. Branicky, May 29 2023

a(16) from Michael S. Branicky, Nov 20 2024