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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). 6
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 (list; graph; refs; listen; history; text; internal format)
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: A017851 A333219 A265537 * A084766 A128559 A122168

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

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Last modified September 20 16:31 EDT 2020. Contains 337265 sequences. (Running on oeis4.)