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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A062370 a(n) = Sum_{i|n,j|n} sigma(i)*sigma(j)/sigma(gcd(i,j)), where sigma(n) = sum of divisors of n. 1
1, 10, 13, 45, 19, 130, 25, 150, 78, 190, 37, 585, 43, 250, 247, 429, 55, 780, 61, 855, 325, 370, 73, 1950, 174, 430, 358, 1125, 91, 2470, 97, 1122, 481, 550, 475, 3510, 115, 610, 559, 2850, 127, 3250, 133, 1665, 1482, 730, 145, 5577, 310, 1740, 715, 1935 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

Multiplicative with a(p^e) = 1 + Sum_{k=1..e} (2k+1)sigma(p^k). - Mitch Harris, May 24 2005

a(n) = Sum_{d|n} tau(d^2)*sigma(d), where tau(k) = A000005(k) and sigma(k) = A000203(k). - Ridouane Oudra, Aug 25 2019

MAPLE

with(numtheory): seq(add(tau(d^2)*sigma(d), d in divisors(n)), n=1..60); # Ridouane Oudra, Aug 25 2019

MATHEMATICA

a[n_] := DivisorSum[n, DivisorSigma[0, #^2] * DivisorSigma[1, #] &]; Array[a, 100] (* Amiram Eldar, Sep 15 2019 *)

PROG

(PARI) a(n) = my(f=factor(n)); for (j=1, #f~, f[j, 1] = 1+ sum(k=1, f[j, 2], (2*k+1)*sigma(f[j, 1]^k)); f[j, 2] = 1); factorback(f); \\ Michel Marcus, Feb 28 2019

CROSSREFS

Cf. A000203, A060648, A000005.

Sequence in context: A102249 A195313 A219829 * A069960 A219715 A154142

Adjacent sequences: A062367 A062368 A062369 * A062371 A062372 A062373

KEYWORD

nonn,mult

AUTHOR

Vladeta Jovovic, Jul 07 2001

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 November 29 09:42 EST 2022. Contains 358423 sequences. (Running on oeis4.)