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!)
A174932 a(n) = Sum_{d|n} A007955(d) * A000027(n/d) = Sum_{d|n} A007955(d) * (n/d), where A007955(m) = product of divisors of m. 1
1, 4, 6, 16, 10, 54, 14, 96, 45, 130, 22, 1860, 26, 238, 270, 1216, 34, 6048, 38, 8300, 504, 550, 46, 335688, 175, 754, 864, 22484, 58, 811050, 62, 35200, 1188, 1258, 1330, 10095048, 74, 1558, 1638, 2576920, 82, 3113586, 86, 86372, 92070, 2254, 94, 255478416 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n) = n*A322671(n). - Andrew Howroyd, Jan 05 2020
EXAMPLE
For n = 4, A007955(n) = b(n): a(4) = b(1)*(4/1) + b(2)*(4/2) + b(4)*(4/4) = 1*4 + 2*2 + 8*1 = 16.
PROG
(PARI) a(n)={n*sumdiv(n, d, vecprod(divisors(d))/d)} \\ Andrew Howroyd, Jan 05 2020
(Magma) [&+[&*Divisors(d)*(n div d):d in Divisors(n)]:n in [1..50]]; // Marius A. Burtea, Jan 05 2020
(Python)
from math import isqrt
from sympy import divisor_count, divisors
def A174932(n): return n*sum(isqrt(d)**(c-2) if (c:=divisor_count(d)) & 1 else d**(c//2-1) for d in divisors(n, generator=True)) # Chai Wah Wu, Jun 25 2022
CROSSREFS
Cf. A007955 (product of divisors), A322671.
Sequence in context: A154784 A328709 A062955 * A359103 A344223 A347263
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Apr 02 2010
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 3 00:41 EST 2024. Contains 370499 sequences. (Running on oeis4.)