|
|
A329856
|
|
Numbers k such that usigma(uphi(k)) = k where usigma is the sum of unitary divisors of k (A034448) and uphi is the unitary totient function (A047994).
|
|
1
|
|
|
1, 3, 4, 5, 8, 9, 12, 17, 20, 24, 32, 36, 40, 68, 72, 96, 128, 136, 160, 257, 288, 384, 544, 640, 1028, 1152, 2056, 2176, 8192, 8224, 24576, 32896, 40960, 44352, 65537, 73728, 131072, 139264, 262148, 393216, 524288, 524296, 655360, 1179648, 1572864, 2097184
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
3 is in the sequence since usigma(uphi(3)) = usigma(2) = 3.
|
|
MATHEMATICA
|
usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); uphi[1] = 1; uphi[n_] := Times @@ (-1 + Power @@@ FactorInteger[n]); Select[Range[10^4], usigma[uphi[#]] == # &]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|