%I #11 Jan 24 2022 16:04:44
%S 7,21,93,357,381,681,1541,7181,24573,36893,192061,388669,393213,
%T 1505533,1572861,10678781,24736253
%N Odd terms in A015782.
%C Odd numbers n such that phi(n)+3 divides sigma(n+3), where phi = A000010 and sigma = A000203.
%e a(3) = 93 is a term because phi(93)+3 = 63 divides sigma(96) = 252 = 4*63.
%p filter:= proc(n) uses numtheory;
%p sigma(n+3) mod (3+phi(n)) = 0
%p end proc:
%p select(filter, [seq(i,i=1..2*10^6,2)]);
%t Select[Range[1, 2*10^6, 2], Divisible[DivisorSigma[1, # + 3], EulerPhi[#] + 3] &] (* _Amiram Eldar_, Jan 24 2022 *)
%Y Cf. A000010, A000203, A015782.
%K nonn,more
%O 1,1
%A _Robert Israel_, Jan 24 2022
%E a(16)-a(17) from _Amiram Eldar_, Jan 24 2022