This site is supported by donations to The OEIS Foundation.

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A033196 a(n) = n^3*Product_{p|n} (1 + 1/p). 3
 1, 12, 36, 96, 150, 432, 392, 768, 972, 1800, 1452, 3456, 2366, 4704, 5400, 6144, 5202, 11664, 7220, 14400, 14112, 17424, 12696, 27648, 18750, 28392, 26244, 37632, 25230, 64800, 30752, 49152, 52272, 62424, 58800, 93312, 52022, 86640 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS T. D. Noe, Table of n, a(n) for n=1..1000 FORMULA Dirichlet g.f.: zeta(s-2)*zeta(s-3)/zeta(2*s-4). a(n) = n^2*A001615(n) = n *A000082(n). Multiplicative with a(p^e) = p^e*p^(2*e-1)*(p+1). - Vladeta Jovovic, Nov 16 2001 a(n) = sum_{d|n} mu(d)*sigma(n^3/d^2). - Benoit Cloitre, Feb 16 2008 a(n) = A001615(n^3) = A001615(n^k)/n^(k-3), with k>2. - Enrique Pérez Herrero, Mar 06 2012 MATHEMATICA a[n_] := n*DivisorSum[n, MoebiusMu[n/#] DivisorSigma[1, #^2]&]; Array[a, 40] (* Jean-François Alcover, Dec 02 2015 *) PROG (PARI) a(n)=direuler(p=2, n, (1+p^2*X)/(1-p^3*X))[n] (PARI) a(n)=sumdiv(n, d, moebius(d)*sigma(n^3/d^2)) \\ Benoit Cloitre, Feb 16 2008 CROSSREFS Sequence in context: A152135 A080562 A212963 * A172218 A172212 A060621 Adjacent sequences:  A033193 A033194 A033195 * A033197 A033198 A033199 KEYWORD nonn,easy,mult AUTHOR EXTENSIONS Additional comments from Michael Somos, May 19 2000 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.