A061468 a(n) = d(n) + phi(n), where d(n) is the number of divisors (A000005) and phi(n) is Euler's totient function (A000010).

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, 22, 18, 30, 16, 32, 22, 24, 20, 28, 21, 38, 22, 28, 24, 42, 20, 44, 26, 30, 26, 48, 26, 45, 26, 36, 30, 54, 26, 44, 32, 40, 32, 60, 28, 62, 34, 42, 39, 52, 28

Offset

1,1

Comments

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

Links

T. D. Noe, Table of n, a(n) for n = 1..1000

Example

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

Maple

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

Mathematica

Table[DivisorSigma[0, n]+EulerPhi[n], {n, 70}] (* Harvey P. Dale, Aug 22 2020 *)

Prog

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

Crossrefs

Cf. A000005, A000010.

Sequence in context: A358506 A333219 A265537 * A343779 A084766 A128559

Adjacent sequences: A061465 A061466 A061467 * A061469 A061470 A061471

Keyword

nonn,easy

Author

Amarnath Murthy, May 04 2001

Extensions

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

Status

approved