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A242416
Numbers whose prime factorization viewed as a tuple of nonzero powers is not palindromic.
6
12, 18, 20, 24, 28, 40, 44, 45, 48, 50, 52, 54, 56, 60, 63, 68, 72, 75, 76, 80, 84, 88, 92, 96, 98, 99, 104, 108, 112, 116, 117, 120, 124, 132, 135, 136, 140, 144, 147, 148, 150, 152, 153, 156, 160, 162, 164, 168, 171, 172, 175, 176, 180, 184, 188, 189, 192, 200
OFFSET
1,1
COMMENTS
These are terms that appear in 2-cycles of permutation A069799.
Complement of A242414.
LINKS
EXAMPLE
12 = p_1^2 * p_2^1 is present, as (2,1) is not a palindrome.
MAPLE
q:= n-> (l-> is(n<>mul(l[i, 1]^l[-i, 2], i=1..nops(l))))(sort(ifactors(n)[2])):
select(q, [$1..200])[]; # Alois P. Heinz, Feb 04 2022
PROG
(Scheme, with Antti Karttunen's IntSeq-library)
(define A242416 (COMPLEMENT 1 A242414))
CROSSREFS
Complement: A242414.
A subsequence of A059404, from which this differs for the first at n=23, as 90 = A059404(23) is not member of this sequence, as the exponents in the prime factorization of 90 = 2^1 * 3^2 * 5^1 form a palindrome, even though 90 is not a power of a squarefree number.
Cf. A069799.
Sequence in context: A376250 A303946 A360246 * A360248 A317616 A375934
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 29 2014
STATUS
approved