1,2

Looking on the number of 1`s, 2`s,...k`s in this sequence we obtain the sequence (1,2,4,5,9,16,25,42,72,...). Lim_k-->oo [number of (k+1)`s / number of(k`s)] = sqrt(e).

Table of n, a(n) for n=1..105.

IntegerPart[Accumulate[1/EulerPhi[Range[110]]]] (* Harvey P. Dale, Dec 19 2015 *)

Cf. A000010

Sequence in context: A156079 A268708 A061555 * A071626 A182008 A106457

Adjacent sequences: A146320 A146321 A146322 * A146324 A146325 A146326

nonn

Ctibor O. Zizka, Oct 30 2008

approved