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Lesser of amicable numbers pair (m, n) such that n = H(m) and m = H(n) where H(n) = A074206(n) is the number of ordered factorizations of n.
1

%I #8 Sep 27 2018 05:04:40

%S 6144,19329024,939524096,4026531840,309237645312,6146186280960,

%T 52158082842624,29273397577908224

%N Lesser of amicable numbers pair (m, n) such that n = H(m) and m = H(n) where H(n) = A074206(n) is the number of ordered factorizations of n.

%C The larger numbers in each pair are in A318252.

%C Analogous to A002025 as A163272 is analogous to A000396.

%C If p and 4p+1 are primes then 2^(4p-1)*p is in this sequence, therefore if A023212 is infinite then also this sequence is.

%C The terms were calculated using an extended list of terms of A025487.

%e 6144 is in the sequence since A074206(6144) = 13312 and A074206(13312) = 6144.

%o (PARI) f(n) = if( n<2, n>0, my(A = divisors(n)); sum(k=1, #A-1, f(A[k])));

%o isok(n)={my(a=f(n)); a>n && f(a)==n;} \\ _Michel Marcus_, Sep 26 2018

%Y Cf. A023212, A074206, A090866, A163272, A318252.

%K nonn,more

%O 1,1

%A _Amiram Eldar_, Aug 22 2018