The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A324990 a(n) = the smallest number k such that floor(sigma(k)/tau(k)) = n, or 0 if no such number k exists. 3
 1, 3, 5, 7, 0, 11, 13, 21, 17, 19, 40, 23, 34, 39, 29, 31, 63, 46, 37, 57, 41, 43, 76, 47, 0, 99, 53, 74, 0, 59, 61, 93, 86, 67, 116, 71, 73, 111, 125, 79, 175, 83, 171, 121, 89, 122, 0, 141, 97, 0, 101, 103, 0, 107, 109, 188, 113, 250, 0, 158, 169, 183, 166 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Floor(sigma(n)/tau(n)) = floor(A000203(n)/A000005(n)) = A057022(n) for n >= 1. Odd primes are terms. a(n) = 0 for numbers n = 5, 25, 29, 47, 50, 53, 59, 83, 89, ... LINKS Robert Israel, Table of n, a(n) for n = 1..2000 EXAMPLE For n = 4; number 7 is the smallest number k with floor(sigma(k)/tau(k)) = 4; floor(sigma(7)/tau(7)) = floor(8/2) = 4. MAPLE N:= 100: # for a(1)..a(N) V:= Vector(N): for k from 1 to N^2 do v:= floor(numtheory:-sigma(k)/numtheory:-tau(k)); if v <= N and V[v]=0 then V[v]:= k fi od: convert(V, list); # Robert Israel, Sep 13 2020 PROG (Magma) Ax:=func; [Ax(n): n in[1..80]] CROSSREFS Cf. A000005, A000203, A057022, A162538, A324991. Sequence in context: A085090 A084713 A162538 * A084712 A031100 A031057 Adjacent sequences: A324987 A324988 A324989 * A324991 A324992 A324993 KEYWORD nonn,look AUTHOR Jaroslav Krizek, Mar 23 2019 STATUS approved

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

Last modified March 29 06:08 EDT 2023. Contains 361596 sequences. (Running on oeis4.)