login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A062351 Palindromic primes with strictly increasing digits up to the middle and then strictly decreasing. 7
2, 3, 5, 7, 11, 131, 151, 181, 191, 353, 373, 383, 787, 797, 12421, 12721, 12821, 13831, 13931, 14741, 17971, 34543, 34843, 35753, 1235321, 1245421, 1257521, 1268621, 1278721, 1456541, 1469641, 1489841, 1579751, 1589851, 3479743 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The last term of the finite series is a(63) = 123467898764321.
LINKS
Nathaniel Johnston, Table of n, a(n) for n = 1..63 (complete sequence)
Patrick De Geest, World of Palindromic Primes
EXAMPLE
13831 belongs to the sequence as it is a palindromic prime in which the digits are increasing up to the middle digit 8 and then decreasing.
PROG
(Python)
from sympy import isprime
from itertools import combinations
def agen():
for digits in range(1, 19):
for left in combinations("123456789", (digits+1)//2):
left = "".join(left)
yield int(left + (left[:digits//2])[::-1])
print(list(filter(isprime, agen()))) # Michael S. Branicky, Apr 25 2021
CROSSREFS
Cf. A343524 (strictly increasing palindromes), A062352, A084836.
Sequence in context: A049575 A070028 A084836 * A185267 A088249 A241724
KEYWORD
nonn,base,easy,fini,full
AUTHOR
Amarnath Murthy, Jun 23 2001
EXTENSIONS
Corrected and edited by Patrick De Geest, Jun 07 2003
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 23 08:25 EDT 2024. Contains 373629 sequences. (Running on oeis4.)