

A328043


Number of divisors of the amicable pairs.


6



12, 6, 12, 12, 12, 12, 12, 12, 16, 12, 16, 16, 32, 16, 20, 10, 24, 12, 20, 20, 32, 32, 48, 24, 32, 16, 48, 24, 48, 24, 20, 20, 24, 16, 32, 16, 20, 20, 20, 20, 32, 16, 24, 24, 36, 12, 24, 12, 48, 16, 32, 16, 20, 20, 18, 36, 20, 20, 48, 48, 32, 16, 32, 16, 32, 16, 32, 16, 32, 16, 48, 24, 32, 16, 48, 32, 24, 20
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..20000


FORMULA

a(n) = A000005(A259180(n)).


EXAMPLE

Consider the first amicable pair [220, 284]. The smaller member has 12 divisors, they are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 220. The larger member has 6 divisors, they are 1, 2, 4, 71, 142, 284. So a(1) = 12 and a(2) = 6.


MATHEMATICA

With[{s = Array[{#, DivisorSigma[1, #]  #} &, 10^5]}, DivisorSigma[0, #] &@ Flatten@ DeleteDuplicates[Sort /@ Select[Reverse /@ s, And[! FreeQ[s, #], UnsameQ @@ #] &]]] (* Michael De Vlieger, Oct 08 2019 *)


CROSSREFS

Row lengths of A328009.
Cf. A000005, A259180, A328063, A328064, A328065.
Sequence in context: A084067 A240537 A227354 * A075247 A257841 A173853
Adjacent sequences: A328040 A328041 A328042 * A328044 A328045 A328046


KEYWORD

nonn


AUTHOR

Omar E. Pol, Oct 02 2019


STATUS

approved



