A087999 a(n) is the LCM of palindromic divisors of n.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 14, 15, 8, 1, 18, 1, 20, 21, 22, 1, 24, 5, 2, 9, 28, 1, 30, 1, 8, 33, 2, 35, 36, 1, 2, 3, 40, 1, 42, 1, 44, 45, 2, 1, 24, 7, 10, 3, 4, 1, 18, 55, 56, 3, 2, 1, 60, 1, 2, 63, 8, 5, 66, 1, 4, 3, 70, 1, 72, 1, 2, 15, 4, 77, 6, 1, 40, 9, 2, 1, 84, 5, 2, 3, 88

Offset: 1

Author

Labos Elemer, Oct 14 2003

Keywords

• base
• nonn

Comments

Sequence is not multiplicative. For example, a(141) = 141 != a(3)*a(47) = 3 * 1. - Franklin T. Adams-Watters, Oct 27 2006

Examples

			n=252: a(252)=252=n,since palindromic divisors = {1,2,3,4,6,7,9,252};
n=255: a(255)=15<n, palind.div ={1,3,5}.
		

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..50000

Crossrefs

Cf. A087990.

Programs

Mathematica

Table[LCM @@ Select[Divisors[k], Reverse[x = IntegerDigits[#]] == x &], {k, 88}] (* Jayanta Basu, Aug 12 2013 *)

PARI

ispal(x) = my(d=digits(x)); d == Vecrev(d);
a(n) = lcm(select(x->ispal(x), divisors(n))); \\ Michel Marcus, Mar 27 2020

Formula

a(n)=1 for non-palindromic primes like 13.