login
Initial digit of phi(n), where phi is Euler totient function, A000010.
2

%I #11 Dec 05 2017 04:05:46

%S 1,1,2,2,4,2,6,4,6,4,1,4,1,6,8,8,1,6,1,8,1,1,2,8,2,1,1,1,2,8,3,1,2,1,

%T 2,1,3,1,2,1,4,1,4,2,2,2,4,1,4,2,3,2,5,1,4,2,3,2,5,1,6,3,3,3,4,2,6,3,

%U 4,2,7,2,7,3,4,3,6,2,7,3,5,4,8,2,6,4,5,4,8,2,7,4,6,4,7,3,9,4,6,4,1,3,1,4,4

%N Initial digit of phi(n), where phi is Euler totient function, A000010.

%H Antti Karttunen, <a href="/A077651/b077651.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A000030(A000010(n)).

%t Table[First[IntegerDigits[EulerPhi[w]]], {w, 1, 128}]

%o (PARI) A077651(n) = (digits(eulerphi(n))[1]); \\ _Antti Karttunen_, Dec 04 2017

%Y Cf. A000030, A000010, A004085.

%K base,nonn

%O 1,3

%A _Labos Elemer_, Nov 19 2002