cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A318251 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.

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%I A318251 #8 Sep 27 2018 05:04:40
%S A318251 6144,19329024,939524096,4026531840,309237645312,6146186280960,
%T A318251 52158082842624,29273397577908224
%N A318251 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 A318251 The larger numbers in each pair are in A318252.
%C A318251 Analogous to A002025 as A163272 is analogous to A000396.
%C A318251 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 A318251 The terms were calculated using an extended list of terms of A025487.
%e A318251 6144 is in the sequence since A074206(6144) = 13312 and A074206(13312) = 6144.
%o A318251 (PARI) f(n) = if( n<2, n>0, my(A = divisors(n)); sum(k=1, #A-1, f(A[k])));
%o A318251 isok(n)={my(a=f(n)); a>n && f(a)==n;} \\ _Michel Marcus_, Sep 26 2018
%Y A318251 Cf. A023212, A074206, A090866, A163272, A318252.
%K A318251 nonn,more
%O A318251 1,1
%A A318251 _Amiram Eldar_, Aug 22 2018