|
|
A051572
|
|
a(1) = 5, a(n) = sigma(a(n-1)).
|
|
6
|
|
|
5, 6, 12, 28, 56, 120, 360, 1170, 3276, 10192, 24738, 61440, 196584, 491520, 1572840, 5433480, 20180160, 94859856, 355532800, 1040179456, 2143289344, 4966055344, 10092086208, 31800637440, 137371852800, 641012414823
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
|
|
PROG
|
(Python)
from itertools import accumulate, repeat # requires Python 3.2 or higher
from sympy import divisor_sigma
A051572_list = list(accumulate(repeat(5, 100), lambda x, _: divisor_sigma(x)))
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|