OFFSET
0,2
COMMENTS
Conjecture: 1.25*n < a(n) < 4*n for n > 0.
EXAMPLE
a(5) = 9 because a(4) = 8 and 5 + phi(a(4)) = 5 + 4 = 9.
MAPLE
a:= proc(n) option remember;
`if`(n=0, 1, n+numtheory[phi](a(n-1)))
end:
seq(a(n), n=0..100); # Alois P. Heinz, May 20 2023
MATHEMATICA
a[0]=1; a[n_]:=a[n]=n+EulerPhi[a[n-1]]; Array[a, 65, 0]
CROSSREFS
KEYWORD
nonn
AUTHOR
Giorgos Kalogeropoulos, May 19 2023
STATUS
approved