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A087999 a(n) is the LCM of palindromic divisors of n. 7
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

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

FORMULA

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

EXAMPLE

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}.

MATHEMATICA

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

PROG

(PARI) ispal(x) = my(d=digits(x)); d == Vecrev(d);

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

CROSSREFS

Cf. A087990.

Sequence in context: A034326 A053833 A167973 * A106614 A297242 A043272

Adjacent sequences: A087996 A087997 A087998 * A088000 A088001 A088002

KEYWORD

base,nonn

AUTHOR

Labos Elemer, Oct 14 2003

STATUS

approved

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Last modified January 31 04:27 EST 2023. Contains 359947 sequences. (Running on oeis4.)