A242416 Numbers whose prime factorization viewed as a tuple of nonzero powers is not palindromic.

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

Alois P. Heinz, Table of n, a(n) for n = 1..10000

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: A059404 A303946 A360246 * A360248 A317616 A332785

Adjacent sequences: A242413 A242414 A242415 * A242417 A242418 A242419

Keyword

nonn

Author

Antti Karttunen, May 29 2014

Status

approved