A064489
a(n) is the smallest number m such that prime(m) has prime(n) decimal digits.
Original entry on oeis.org
5, 26, 1230, 78499, 455052512, 37607912019, 279238341033926, 24739954287740861, 201467286689315906291, 157589269275973410412739599
Offset: 1
For n = 1: a(1) = 5 because prime(5) = 11 is the first prime with 2 = prime(1) decimal digits.
-
l(n)=ln=0; while(n,n=floor(n/10); ln++); return(ln);
a=0; for(n=1,10^6,x=l(prime(n)); if(isprime(x),b=x; if(b>a,a=b; print1(n, ", "))))
-
from sympy import prime, nextprime, primepi
def a(n): return primepi(nextprime(10**(prime(n)-1)))
print([a(n) for n in range(1, 6)]) # Michael S. Branicky, May 26 2021
A133836
Largest prime with number of decimal digits equal to n-th prime.
Original entry on oeis.org
97, 997, 99991, 9999991, 99999999977, 9999999999971, 99999999999999997, 9999999999999999961, 99999999999999999999977, 99999999999999999999999999973, 9999999999999999999999999999973
Offset: 1
97 is the largest prime with 2 digits.
997 is the largest prime with 3 digits.
99991 is the largest prime with 5 digits.
A133833
Smallest and largest primes with number of decimal digits equal to n-th prime.
Original entry on oeis.org
11, 97, 101, 997, 10007, 99991, 1000003, 9999991, 10000000019, 99999999977, 1000000000039, 9999999999971, 10000000000000061, 99999999999999997, 1000000000000000003, 9999999999999999961
Offset: 1
11, 97 are respectively the smallest and the largest 2-digit primes.
101, 997 are respectively the smallest and the largest 3-digit primes.
10007, 99991 are respectively the smallest and the largest 5-digit primes.
-
Table[{NextPrime[10^(n-1)],NextPrime[10^n,-1]},{n,Prime[Range[8]]}] // Flatten (* Harvey P. Dale, Nov 21 2018 *)
Showing 1-3 of 3 results.