OFFSET
1,1
COMMENTS
Square roots of squares present in A348753.
Any hypothetical odd term y of A005820 must by necessity be a square. If y is also a nonmultiple of 3, then the square root x = A000196(y) of such a number y must satisfy the condition that for all nontrivial unitary divisor pairs d and x/d [with gcd(d,x/d) = 1, 1 < d < x], the other unitary divisor (d) should reside in this sequence, and the other divisor (x/d) in A348936. The explanation is similar to the one given in A348738. See also comments in A348933.
In range 1..2^20, there are 256143 numbers in this sequence and 93381 numbers in A348936.
The composites in this sequence are: 133, 217, 247, 259, 299, 301, 335, 341, 371, etc.
LINKS
MATHEMATICA
f[2, e_] := 1; f[p_, e_] := NextPrime[p, -1]^e; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[400], MemberQ[{1, 5}, Mod[#, 6]] && s[s[DivisorSigma[1, #^2]]] < s[s[#^2]] &] (* Amiram Eldar, Nov 04 2021 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 04 2021
STATUS
approved