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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A345279 a(n) = Sum_{p|n} p^((pi(p)+1) mod 2). 1
0, 1, 3, 1, 1, 4, 7, 1, 3, 2, 1, 4, 13, 8, 4, 1, 1, 4, 19, 2, 10, 2, 1, 4, 1, 14, 3, 8, 29, 5, 1, 1, 4, 2, 8, 4, 37, 20, 16, 2, 1, 11, 43, 2, 4, 2, 1, 4, 7, 2, 4, 14, 53, 4, 2, 8, 22, 30, 1, 5, 61, 2, 10, 1, 14, 5, 1, 2, 4, 9, 71, 4, 1, 38, 4, 20, 8, 17, 79, 2, 3, 2, 1, 11, 2, 44 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..86.

EXAMPLE

a(15) = Sum_{p|15} p^((pi(p)+1) mod 2) = 3^1 + 5^0 = 4.

MATHEMATICA

Table[Sum[k^Mod[PrimePi[k] + 1, 2] (PrimePi[k] - PrimePi[k - 1]) (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 100}]

CROSSREFS

Cf. A000720 (pi), A345278.

Sequence in context: A209172 A263950 A160870 * A342447 A025255 A296006

Adjacent sequences:  A345276 A345277 A345278 * A345280 A345281 A345282

KEYWORD

nonn

AUTHOR

Wesley Ivan Hurt, Jun 12 2021

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 January 24 13:48 EST 2022. Contains 350538 sequences. (Running on oeis4.)