The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A274546

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A274546

Numbers m such that 5*m is squarefree.
(history; published version)

#44 by OEIS Server at Tue Sep 26 01:57:52 EDT 2023

LINKS

Amiram Eldar, <a href="/A274546/b274546_1.txt">Table of n, a(n) for n = 1..10000</a>

#43 by Joerg Arndt at Tue Sep 26 01:57:52 EDT 2023

STATUS

reviewed

approved

Discussion

Tue Sep 26

01:57

OEIS Server: Installed first b-file as b274546.txt.

#42 by Michel Marcus at Tue Sep 26 01:49:17 EDT 2023

STATUS

proposed

reviewed

#41 by Amiram Eldar at Tue Sep 26 01:43:22 EDT 2023

STATUS

editing

proposed

#40 by Amiram Eldar at Tue Sep 26 01:26:36 EDT 2023

LINKS

Amiram Eldar, <a href="/A274546/b274546_1.txt">Table of n, a(n) for n = 1..10000</a>

#39 by Amiram Eldar at Tue Sep 26 01:26:10 EDT 2023

NAME

Numbers k m such that 5*k m is squarefree.

CROSSREFS

Numbers n m such that nm*A005117(k) is squarefree: A005117 (k = 1), A056911 (k = 2), A261034 (k = 3), this sequence (k = 5), A276378 (k = 6).

#38 by Amiram Eldar at Tue Sep 26 01:25:41 EDT 2023

FORMULA

Sum_{n>=1} 1/a(n)^s = (5^s)*zeta(s)/((1+5^s)*zeta(2*s)), s>1. - Amiram Eldar, Sep 26 2023

MATHEMATICA

Select[Range[135], !Divisible[#, 5] && SquareFreeQ[#] &] (* Amiram Eldar, Sep 26 2023 *)

CROSSREFS

Numbers n such that n*A005117(k) is squarefree: A005117 (k = 1), A056911 (k = 2), A261034 (k = 3), this sequence (k = 45), A276378 (k = 6).

#37 by Amiram Eldar at Tue Sep 26 01:25:12 EDT 2023

NAME

Numbers n k such that 5n 5*k is squarefree.

#36 by Amiram Eldar at Tue Sep 26 01:24:47 EDT 2023

FORMULA

a(n) ~ 5n/Pi^2*n/5. - Charles R Greathouse IV, Sep 06 2016 [corrected by _Amiram Eldar_, Sep 26 2023]

STATUS

approved

editing

#35 by Charles R Greathouse IV at Thu Sep 08 08:46:17 EDT 2022

PROG

(MAGMAMagma) [n: n in [1..135] | IsSquarefree(5*n)];

Discussion

Thu Sep 08

08:46

OEIS Server: https://oeis.org/edit/global/2944