OFFSET
1,2
COMMENTS
Numbers n such that either all exponents in the prime factorization of n (cf. A124010) are even or all are = 1.
Every positive integer can be expressed as the product of two elements of this sequence. Every integer > 1 can be expressed as the product of two distinct members of the sequence. - Franklin T. Adams-Watters, Apr 08 2016
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Square Number
Eric Weisstein's World of Mathematics, Squarefree
Wikipedia, Squarefree integer
Wikipedia, Square number
PROG
(Haskell)
a210490 n = a210490_list !! (n-1)
a210490_list = filter chi [1..] where
chi x = all (== 1) es || all even es where es = a124010_row x
(PARI) isok(m) = issquare(m) || issquarefree(m); \\ Michel Marcus, Feb 03 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jan 24 2013
EXTENSIONS
A more precise name from Michel Marcus, Feb 03 2022
STATUS
approved