A227228 Palindromes greater than 10 whose sum of proper divisors is also a palindrome greater than 10.

333, 646, 656, 979, 1001, 3553, 10801, 11111, 18581, 31713, 34943, 48484, 57375, 95259, 99099, 158851, 262262, 569965, 1173711, 1216121, 1399931, 1439341, 1502051, 1925291, 3203023, 3436343, 3659563, 3662663, 3803083, 3888883, 5185815, 5352535, 5893985

Offset

1,1

Comments

The palindromic primes (A002385) (whose sum of proper divisors is 1) are not included in this sequence.

Links

Donovan Johnson, Table of n, a(n) for n = 1..260 (terms < 10^14)

Example

10801 = 1543*7*1 and 1543 + 7 + 1 = 1551 (a palindrome). So, 10801 is a member of this sequence.

Prog

(Python)
from sympy import divisors
def rev(n):
..r = ''
..for i in str(n):
....r = i + r
..return int(r)
for i in range(10**6):
..s = sum(divisors(i))-i
..if rev(i) == i and s > 10 and rev(s) == s:
....print(i, end=', ')
# simplified by Derek Orr, Oct 16 2014

Crossrefs

Cf. A002113, A001065, A002385.

Sequence in context: A158081 A248062 A056089 * A066801 A066349 A043503

Adjacent sequences: A227225 A227226 A227227 * A227229 A227230 A227231

Keyword

nonn,base

Author

Derek Orr, Sep 19 2013

Status

approved