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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A338713 Number of numbers of the form i*n with 1 <= i <= n and tau(i*n) = 4. 2
0, 0, 1, 1, 2, 1, 3, 1, 1, 1, 4, 0, 5, 1, 1, 0, 6, 0, 7, 0, 1, 1, 8, 0, 1, 1, 1, 0, 9, 0, 10, 0, 1, 1, 1, 0, 11, 1, 1, 0, 12, 0, 13, 0, 0, 1, 14, 0, 1, 0, 1, 0, 15, 0, 1, 0, 1, 1, 16, 0, 17, 1, 0, 0, 1, 0, 18, 0, 1, 0, 19, 0, 20, 1, 0, 0, 1, 0, 21, 0, 0, 1, 22, 0, 1, 1, 1, 0, 23 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

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

PROG

(PARI) a(n) = sum(i=1, n, numdiv(i*n)==4); \\ Michel Marcus, Nov 11 2020

CROSSREFS

tau is A000005.

For tau(i*n) = 2, 3, 6, see A010051, A296084, A338714.

Inspired by A333995.

Sequence in context: A320077 A325522 A006083 * A080301 A326674 A331184

Adjacent sequences:  A338710 A338711 A338712 * A338714 A338715 A338716

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Nov 11 2020

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 June 13 17:14 EDT 2021. Contains 345008 sequences. (Running on oeis4.)