login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A061091 Number of k with 1 <= k <= n relatively prime to phi(k). 2
1, 2, 3, 3, 4, 4, 5, 5, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 16, 16, 16, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 21, 21, 21, 21, 21, 21, 22, 22, 23, 23, 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 28, 28, 28 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

lim_{n->oo} a(n) * log(log(log( n ))) / n = 1 / exp( gamma ).

REFERENCES

S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 115-119.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

P. Erdős, Some asymptotic formulas in number theory, J. Indian Math. Soc. 12 (1948) 75-78.

S. R. Finch, Euler Totient Function Asymptotic Constants

Z. Ruzsa, Erdős and the integers, J. Number Theory 79 (1999) 115-163.

FORMULA

a(n) = sum of GCD( k, phi(k)) = 1 for 0 < k <= n.

a(1) = 1, a(n) = a(n-1) + A297086(n). - Iain Fox, Dec 25 2017

PROG

(PARI) a(n) = sum(k=1, n, gcd(k, eulerphi(k)) == 1) \\ Charles R Greathouse IV, Jan 29 2013 (corrected by Iain Fox, Dec 25 2017)

CROSSREFS

Gamma function: A001620, phi function: A000010.

Sequence in context: A185195 A192512 A036234 * A196241 A086592 A279783

Adjacent sequences:  A061088 A061089 A061090 * A061092 A061093 A061094

KEYWORD

nonn,easy

AUTHOR

Frank Ellermann, May 29 2001

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 22 04:32 EDT 2019. Contains 321406 sequences. (Running on oeis4.)