|
|
A280133
|
|
Partial products of A057661 (Sum_{d|n} psi(d)).
|
|
1
|
|
|
1, 2, 8, 48, 528, 5808, 127776, 2811072, 87143232, 2788583424, 156160671744, 6090266198016, 481131029643264, 31273516926812160, 2314240252584099840, 199024661722232586240, 27266378655945864314880, 2508506836347019516968960, 431463175851687356918661120
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
psi(n) is the sum of the totatives of n (A023896).
|
|
LINKS
|
|
|
FORMULA
|
a(n) = Product_{i=1..n} A057661(i).
|
|
MATHEMATICA
|
FoldList[Times[#1, #2] &, Array[Sum[Total@ Select[Range@ d, CoprimeQ[#, d] &], {d, Divisors@ #}] &, 19]] (* Michael De Vlieger, Dec 27 2016 *)
|
|
PROG
|
(Magma) [&*[&+[&+[h: h in [1..d] | GCD(h, d) eq 1]: d in Divisors(k)]: k in [1..n]]: n in [1..1000]]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|