The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A129139 a(n) = number of positive integers which are coprime to n and are <= d(n), where d(n) = A000005(n). 1
 1, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 3, 2, 2, 3, 3, 2, 3, 3, 2, 2, 2, 3, 3, 2, 4, 3, 2, 2, 3, 3, 2, 2, 2, 3, 3, 2, 2, 3, 3, 2, 3, 3, 2, 3, 4, 3, 3, 2, 2, 3, 2, 2, 4, 4, 4, 3, 2, 3, 3, 2, 2, 4, 2, 2, 3, 3, 4, 3, 2, 4, 4, 2, 2, 3, 4, 2, 3, 4, 2, 3, 4, 3, 3, 2, 4, 4, 2, 3, 4, 4, 2, 3, 2, 4, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE d(16) = 5. So a(16) is the number of integers coprime to 16 which are <= 5. There are 3 such integers: 1, 3, 5; so a(16) = 3. MAPLE with(numtheory): a:=proc(n) local ct, j: ct:=0: for j from 1 to tau(n) do if gcd(j, n)=1 then ct:=ct+1 else fi od: ct; end: seq(a(n), n=1..140); # Emeric Deutsch, Apr 02 2007 CROSSREFS Cf. A129138, A126131, A074919. Sequence in context: A251139 A195061 A064130 * A032539 A122922 A278570 Adjacent sequences:  A129136 A129137 A129138 * A129140 A129141 A129142 KEYWORD nonn AUTHOR Leroy Quet, Mar 30 2007 EXTENSIONS More terms from Emeric Deutsch, Apr 02 2007 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.

Last modified September 27 22:36 EDT 2020. Contains 337388 sequences. (Running on oeis4.)