A261881
Minimal nested palindromic primes with seed 0.
Original entry on oeis.org
0, 101, 31013, 3310133, 933101339, 1093310133901, 30109331013390103, 333010933101339010333, 33330109331013390103333, 993333010933101339010333399, 104993333010933101339010333399401, 7810499333301093310133901033339940187
Offset: 1
As a triangle:
........0
.......101
......31013
.....3310133
....933101339
..1093310133901
30109331013390103
-
s = {0}; Do[NestWhile[# + 1 &, 1, ! PrimeQ[tmp = FromDigits[Join[#, IntegerDigits[Last[s]], Reverse[#]] &[IntegerDigits[#]]]] &]; AppendTo[s, tmp], {15}]; s
(* Peter J. C. Moses, Sep 01 2015 *)
A375690
a(1) = 3; for n > 1, a(n) is the smallest palindromic prime containing exactly 2 more digits on each end than a(n-1), with a(n-1) as the central substring.
Original entry on oeis.org
3, 10301, 101030101, 1210103010121, 12121010301012121, 111212101030101212111, 3111121210103010121211113, 17311112121010301012121111371, 961731111212101030101212111137169, 3196173111121210103010121211113716913, 95319617311112121010301012121111371691359, 109531961731111212101030101212111137169135901, 1410953196173111121210103010121211113716913590141, 13141095319617311112121010301012121111371691359014131
Offset: 1
As a triangle:
3
10301
101030101
1210103010121
12121010301012121
-
from sympy import isprime
from itertools import product
def agen(): # generator of terms
an, s = 3, "3"
while an > 0:
yield an
an = -1
for f, r in product("1379", "0123456789"):
sn = f+r+s+r+f
if isprime(t:=int(sn)):
an, s = t, sn
break
print(list(agen())) # Michael S. Branicky, Aug 25 2024
A376103
a(1) = 5; for n > 1, a(n) is the smallest palindromic prime containing exactly 2 more digits on each end than a(n-1), with a(n-1) as the central substring.
Original entry on oeis.org
5, 10501, 111050111, 1211105011121, 39121110501112193, 393912111050111219393, 7239391211105011121939327, 79723939121110501112193932797, 157972393912111050111219393279751, 7415797239391211105011121939327975147
Offset: 1
As a triangle:
5
10501
111050111
1211105011121
39121110501112193
Showing 1-3 of 3 results.
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