OFFSET
1,5
FORMULA
a(1) = a(2) = 1; for n>2, a(n) = Product_{i=3..n} A049820(i).
MATHEMATICA
FoldList[#1 #2 &, Table[Boole[n <= 2] + n - DivisorSigma[0, n], {n, 25}]] (* Michael De Vlieger, Jan 11 2017 *)
PROG
(Magma) [1, 1] cat [&*[#[c: c in [1..k] | k mod c ne 0]: k in [3..n]]: n in [3..100]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jan 11 2017
STATUS
approved