Dris index odd is impossible when has at least two odd prime factors
OpenOddPerfectNumber.no_dris_two_odd_primes_coreLet be a prime, let be such that has at least two odd prime divisors, let be odd with , and let be odd with . Then the Dris relations
cannot both hold; equivalently, there is no odd perfect number in Euler form whose Dris index is at least , for such an exponent .
This is the complement, in the special exponent , of the case already isolated on the platform: when has at most one odd prime divisor, an index that is or an odd prime is ruled out by known results, and the remaining composite case is recorded as OddPerfectNumber.no_dris_one_odd_prime_core. The present statement is the residual core for all other exponents, that is, whenever carries two or more distinct odd primes; it generalises the exponent-specific core OddPerfectNumber.no_dris_thirteen_core from with to an arbitrary prime and an arbitrary .
The difficulty is that the standard counting bound for the prime support of , namely , becomes weaker precisely when has several odd prime factors, so Sylvester's bound no longer yields a contradiction.
import Mathlib open Finset
namespace OddPerfectNumber
theorem no_dris_two_odd_primes_core (p k m s : Nat)
(hp : p.Prime) (hk : k ≠ 0) (hm : Odd m) (hpm : ¬ p ∣ m)
(hk2 : 2 ≤ ((k + 1).primeFactors.erase 2).card)
(hs2 : 2 ≤ s) (hs_not_even : ¬ Even s) (hs_dvd : s ∣ m ^ 2) :
¬ (2 * m ^ 2 = (∑ d ∈ (p ^ k).divisors, d) * s ∧
(∑ d ∈ (m ^ 2).divisors, d) = p ^ k * s) := by
sorry
end OddPerfectNumber