OFFSET
1,2
COMMENTS
Closed under multiplication.
LINKS
FORMULA
MATHEMATICA
q[n_] := n == 1 || AllTrue[FactorInteger[n], Mod[First[#], 4] == 1 && Last[#] > 1 &]; Select[Range[50000], q]
PROG
(PARI) is(n) = {my(f = factor(n)); for(i = 1, #f~, if(f[i, 1]%4 != 1 || f[i, 2] == 1, return(0))); 1; }
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Jan 26 2024
STATUS
approved