A069588 Smallest prime in which the n-th significant digit is a 1.

11, 11, 101, 1009, 10007, 100003, 1000003, 10000019, 100000007, 1000000007, 10000000019, 100000000003, 1000000000039, 10000000000037, 100000000000031, 1000000000000037, 10000000000000061, 100000000000000003, 1000000000000000003, 10000000000000000051

Offset

1,1

Comments

Essentially (i.e., except for the initial term), the same as A003617. The definition is misleading, since "n-th significant digit" seems to mean here "most significant digit" (except for a(1)), while the "significance" is decreasing when going from the first to the last digit. (E.g., 1234 rounded to 2 significant digits is 1200, so "1,2" should be the first and second (and not fourth and third) significant digits.) [M. F. Hasler, Jun 03 2009]

Links

Michael S. Branicky, Table of n, a(n) for n = 1..1000

Maple

11, seq(nextprime(10^j), j=1..30);

Prog

(Python)
from sympy import nextprime
def a(n): return 11 if n == 1 else nextprime(10**(n-1))
print([a(n) for n in range(1, 21)]) # Michael S. Branicky, Nov 11 2021

Crossrefs

Sequence in context: A088772 A088771 A088773 * A088774 A255745 A188548

Adjacent sequences: A069585 A069586 A069587 * A069589 A069590 A069591

Keyword

nonn,base

Author

Amarnath Murthy, Mar 25 2002

Extensions

More terms from Sascha Kurz, Mar 28 2002

a(19) and beyond from Michael S. Branicky, Nov 11 2021

Status

approved