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

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A143272 a(n) = d(n)*T(n), where d(n) is the number of divisors of n (A000005) and T(n)=n(n+1)/2 are the triangular numbers (A000217). 2
 1, 6, 12, 30, 30, 84, 56, 144, 135, 220, 132, 468, 182, 420, 480, 680, 306, 1026, 380, 1260, 924, 1012, 552, 2400, 975, 1404, 1512, 2436, 870, 3720, 992, 3168, 2244, 2380, 2520, 5994, 1406, 2964, 3120, 6560, 1722, 7224, 1892, 5940, 6210, 4324, 2256, 11760 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 FORMULA Equals row sums of triangle A143271 EXAMPLE a(4) = 30 = d(4)*T(4) = 3*10, where A000005 = (1, 2, 2, 3, 2, 4, ...) and A000217 = (1, 3, 6, 10, ...). MAPLE with(numtheory): seq((1/2)*tau(n)*n*(n+1), n=1..50); # Emeric Deutsch, Aug 16 2008 MATHEMATICA Table[DivisorSigma[0, n] (n(n+1))/2, {n, 50}] (* Harvey P. Dale, Sep 05 2017 *) PROG (PARI) a(n) = numdiv(n)*n*(n+1)/2; \\ Michel Marcus, Mar 11 2019 CROSSREFS Cf. A143271, A000005, A000217. Sequence in context: A079390 A124679 A242949 * A153877 A229491 A263676 Adjacent sequences:  A143269 A143270 A143271 * A143273 A143274 A143275 KEYWORD nonn AUTHOR Gary W. Adamson, Aug 03 2008 EXTENSIONS Extended by Emeric Deutsch, Aug 16 2008 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.

Last modified November 25 09:29 EST 2020. Contains 338623 sequences. (Running on oeis4.)