OFFSET
1,2
COMMENTS
It can be shown that this is a subsequence of A028982.
From Robert Israel, Jul 09 2018: (Start)
The only terms that are not in A062503 are 2, 8 and 18.
No term is divisible by a term of A002476.
p^2 is a term for every p in A003627. (End)
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
Mathematics StackExchange, Are 1+p^3+p^6 and 1+p^4+p^8 coprime?
MAPLE
N:= 10^6: # to get all terms <= N
sort(select(filter, [seq(t^2, t=1..isqrt(N)), seq(2*t^2, t=1..isqrt(N/2))])); # Robert Israel, Jul 09 2018
MATHEMATICA
Select[Range[25000], CoprimeQ[DivisorSigma[3, #], DivisorSigma[4, #]] &] (* Michael De Vlieger, Aug 10 2023 *)
PROG
(PARI) isok(n) = gcd(sigma(n, 3), sigma(n, 4)) == 1; \\ Michel Marcus, Sep 24 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved