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A068837
Smallest prime with concatenation of first n odd numbers as leading digits.
2
11, 13, 13513, 13577, 135799, 135791107, 13579111307, 1357911131503, 13579111315171, 135791113151719, 1357911131517192157, 13579111315171921231, 135791113151719212325007, 1357911131517192123252763, 13579111315171921232527291, 135791113151719212325272931
OFFSET
1,1
COMMENTS
a(351) has 1002 digits. - Michael S. Branicky, Mar 19 2024
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..350
PROG
(Python)
from sympy import isprime
from itertools import count
def a(n):
prefix = int("".join(map(str, (2*i+1 for i in range(n)))))
if isprime(prefix): return prefix
for extra in count(1):
prefix *= 10
for i in range(10**extra):
t = prefix + i
if isprime(t): return t
print([a(n) for n in range(1, 17)]) # Michael S. Branicky, Mar 19 2024
CROSSREFS
Sequence in context: A360388 A096074 A288611 * A246627 A257135 A357046
KEYWORD
nonn,base
AUTHOR
Amarnath Murthy, Mar 09 2002
EXTENSIONS
More terms from Benoit Cloitre, Mar 10 2002
a(10) corrected by Jayanta Basu, Aug 08 2013
a(6)-a(8) and a(13) corrected and more terms from Sean A. Irvine, Mar 17 2024
STATUS
approved