A082617 a(1) = 1, then squarefree palindromes such that a(n+1) = p*a(n) where p is a prime not dividing any previous term.

1, 2, 6, 66, 858, 6006, 222222, 22444422, 204042240402, 2010020110200102, 263312634436213362, 205221063132933339231360122502

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Example

a(4) = 66, a(5) = 858 = 13*66.

Prog

(Python)
from sympy import factorint, nextprime
A082617_list, a = [1], 1
for _ in range(10):
....p = 2
....b = p*a
....bs = str(b)
....while bs != bs[::-1] or max(factorint(b).values()) > 1:
........p = nextprime(p)
........b = p*a
........bs = str(b)
....A082617_list.append(b)
....a = b # Chai Wah Wu, Jun 09 2015

Crossrefs

Cf. A082618.

Sequence in context: A335645 A082619 A046399 * A006517 A217630 A091458

Adjacent sequences: A082614 A082615 A082616 * A082618 A082619 A082620

Keyword

more,nonn,base

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Apr 29 2003

Extensions

More terms from R. J. Mathar, Jul 15 2007

Corrected example by Chai Wah Wu, Jun 09 2015

a(12) from Giovanni Resta, Jun 11 2015

Status

approved