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A334392 Numbers m such that the LCM of their palindromic divisors is neither 1 nor m. 1
16, 25, 26, 27, 32, 34, 38, 39, 46, 48, 49, 50, 51, 52, 54, 57, 58, 62, 64, 65, 68, 69, 74, 75, 76, 78, 80, 81, 82, 85, 86, 87, 91, 92, 93, 94, 95, 96, 98, 100, 102, 104, 106, 108, 112, 114, 115, 116, 117, 118, 119, 122, 123, 124, 125, 128, 129, 130, 133, 134 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A334139, A334391 and this sequence form a partition of the set of positive integers N* (A000027).

The integers {2^k, k >= 4, 2^k non-palindrome} form a subsequence whose first few terms are : 16, 32, 64, 128, ...

LINKS

Table of n, a(n) for n=1..60.

Wikipedia, Partition of a set

EXAMPLE

50 has 3 palindromic divisors {1, 2, 5} then A087999(50) = 10 and 50 is a term.

MATHEMATICA

Select[Range[125], !MemberQ[{1, #}, LCM @@ Select[Divisors[#], PalindromeQ]] &] (* Amiram Eldar, May 05 2020 *)

PROG

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

isok(m) = my(d=divisors(m), lcmpd = lcm(select(x->ispal(x), d))); (lcmpd != 1) && (lcmpd != m); \\ Michel Marcus, May 05 2020

CROSSREFS

Cf. A087990, A087999.

Cf. A334391 [LCM(palindromic divisors of m) = 1], A334139 [LCM(palindromic divisors of m) = m], this sequence [LCM(palindromic divisors of m) != 1 and != m].

Sequence in context: A170985 A202335 A071524 * A227651 A095409 A339624

Adjacent sequences:  A334389 A334390 A334391 * A334393 A334394 A334395

KEYWORD

nonn,base

AUTHOR

Bernard Schott, May 04 2020

STATUS

approved

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Last modified July 28 19:33 EDT 2021. Contains 346335 sequences. (Running on oeis4.)