OFFSET
0,1
COMMENTS
a(32) has 1057 digits. - Michael S. Branicky, Sep 29 2024
LINKS
Michael S. Branicky, Table of n, a(n) for n = 0..31
EXAMPLE
a(1) = 727, because 727 is prime and no lesser number verify this property.
As a triangle:
2
727
1572751
1081572751801
100210815727518012001
1001410021081572751801200141001
1000141001410021081572751801200141001410001
100001610001410014100210815727518012001410014100016100001
1000005310000161000141001410021081572751801200141001410001610000135000001
PROG
(Python)
from itertools import count, islice
from sympy import isprime
def A375956_gen(): # generator of terms
a, l, r = 2, 1, 10
yield 2
for n in count(1):
b = 10**n
c = b*r
for i in count(10**(n-1)):
m = c*i+a*b+int(str(i)[::-1])
if isprime(m):
yield m
a = m
l += n<<1
r *= 10**(n<<1)
break
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jean-Marc Rebert, Sep 03 2024
STATUS
approved