

A307051


Lesser of amicable numbers pair m < n such that A307037(m) = n and A307037(n) = m.


1



4, 16, 68, 256, 1028, 4112, 7200, 65536, 262148, 921600, 1036800, 1048592, 16777472, 88218000, 371404800, 418535784576
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OFFSET

1,1


COMMENTS

The larger counterparts are in A307052.
Includes all the pairs of the form {F(k)1, F(k)} with 0 < k, where F(k) = 2^(2^k) + 1, the kth Fermat number, is prime.
Includes all the pairs of the form {(F(k)1)*F(m), F(k)*(F(m)1)} with 0 < k < m, where both F(k) and F(m) are primes.
a(17) > 4*10^12.  Giovanni Resta, Mar 24 2019


LINKS

Table of n, a(n) for n=1..16.


MATHEMATICA

f[p_, e_] := p^e + (1)^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; s={}; Do[m = a[n]; If[m > n && a[m] == n, AppendTo[s, n]], {n, 1, 10^7}]; s


CROSSREFS

Cf. A000215, A307037, A307038, A307052.
Sequence in context: A292759 A259815 A283036 * A158761 A179611 A290912
Adjacent sequences: A307048 A307049 A307050 * A307052 A307053 A307054


KEYWORD

nonn,more


AUTHOR

Amiram Eldar, Mar 21 2019


EXTENSIONS

a(16) from Giovanni Resta, Mar 24 2019


STATUS

approved



