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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).
10
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.
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
Sequence in context: A358506 A333219 A265537 * A343779 A084766 A128559
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