OFFSET
1,3
COMMENTS
A023896(n) = the sum of totatives of n.
a(n) = n! for n = 1, 5 and 6.
FORMULA
a(n) = Sum_{i=1..n} A023896(i).
MATHEMATICA
FoldList[#1 #2 &, Table[Ceiling[(n EulerPhi@ n)/2], {n, 20}]] (* Michael De Vlieger, Jan 03 2017 *)
PROG
(Magma) [&*[&+[h: h in [1..k] | GCD(h, k) eq 1]: k in [1..n]]: n in [1..100]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jan 03 2017
STATUS
approved