OFFSET
1,1
COMMENTS
All the listed terms are even squarefree numbers.
Subsequence of A039956.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
a(2) = 6 = 2 * 3: 6^2 + 1 = 37 = 1 * 37; 6^2 - 1 = 35 = 5 * 7; 6, 37, 35 are all squarefree.
MAPLE
select(n -> andmap(issqrfree, [n, n^2+1, n^2-1]), [seq(n, n=2.. 10^3)]);
MATHEMATICA
Select[Range[1000], SquareFreeQ[#] && SquareFreeQ[#^2 + 1] && SquareFreeQ[#^2 - 1] &]
PROG
(PARI) for(n=2, 1000, issquarefree(n) & issquarefree(n^2 + 1) & issquarefree(n^2 - 1) & print1(n, ", "))
(Magma) [n : n in [1..1000] | IsSquarefree(n) and IsSquarefree(n^2+1) and IsSquarefree(n^2-1) ];
CROSSREFS
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Feb 09 2016
STATUS
approved