OFFSET
1,1
COMMENTS
The asymptotic density of this sequence within A001481 is zero. More precisely, the number of terms that do not exceed x is ~ o(x/sqrt(log(x))) (Jakimczuk, 2024, Theorem 4.10, p. 55).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Rafael Jakimczuk, Generalizations of Mertens's Formula and k-Free and s-Full Numbers with Prime Divisors in Arithmetic Progression, ResearchGate, 2024.
MATHEMATICA
Select[Range[1500], SquaresR[2, #] > 0 && FactorInteger[#][[-1 , 2]] > 1 &]
PROG
(PARI) is(n) = {my(f=factor(n)); if(n == 1 || f[#f~, 2] == 1, return(0)); for(i=1, #f~, if(f[i, 2]%2 && f[i, 1]%4 == 3, return(0))); 1; }
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Amiram Eldar, Mar 08 2024
STATUS
approved