A061468 - OEIS

%I #15 Aug 22 2020 13:08:06

%S 2,3,4,5,6,6,8,8,9,8,12,10,14,10,12,13,18,12,20,14,16,14,24,16,23,16,

%T 22,18,30,16,32,22,24,20,28,21,38,22,28,24,42,20,44,26,30,26,48,26,45,

%U 26,36,30,54,26,44,32,40,32,60,28,62,34,42,39,52,28

%N a(n) = d(n) + phi(n), where d(n) is the number of divisors (A000005) and phi(n) is Euler's totient function (A000010).

%C If d(n) increases phi(n) tends to go down so the sum has a significance.

%H T. D. Noe, <a href="/A061468/b061468.txt">Table of n, a(n) for n = 1..1000</a>

%e a(20) = d(20) + phi(20) = 6 + 8 = 14.

%p with(numtheory); A061468 := n-> tau(n) + phi(n);

%t Table[DivisorSigma[0,n]+EulerPhi[n],{n,70}] (* _Harvey P. Dale_, Aug 22 2020 *)

%o (PARI) { for (n=1, 1000, write("b061468.txt", n, " ", numdiv(n) + eulerphi(n)) ) } \\ _Harry J. Smith_, Jul 23 2009

%Y Cf. A000005, A000010.

%K nonn,easy

%O 1,1

%A _Amarnath Murthy_, May 04 2001

%E More terms from Winston C. Yang (winston(AT)cs.wisc.edu), May 19 2001