This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A051193 a(n) = Sum_{k=1..n} lcm(n,k). 9
 1, 4, 12, 24, 55, 66, 154, 176, 279, 320, 616, 468, 1027, 910, 1110, 1376, 2329, 1656, 3268, 2320, 3171, 3674, 5842, 3624, 6525, 6136, 7398, 6636, 11803, 6630, 14446, 10944, 12837, 13940, 15820, 12096, 24679, 19570, 21450, 18080, 33661, 18984, 38872, 26884 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Akshay Bansal, Table of n, a(n) for n = 1..10000 (terms 1..1000 from T. D. Noe) Akshay Bansal, C Program Soichi Ikeda and Kaneaki Matsuoka, On the Lcm-Sum Function, Journal of Integer Sequences, Vol. 17 (2014), Article 14.1.7. Laszlo Toth, Weighted gcd-sum functions, J. Integer Sequences, 14 (2011), Article 11.7.7 FORMULA a(n) = n*(1+Sum_{d|n} d*phi(d))/2 = n*(1+A057660(n))/2 = n*A057661(n). - Vladeta Jovovic, Jun 21 2002 G.f.: x*f'(x), where f(x) = x/(2*(1 - x)) + (1/2)*Sum_{k>=1} k*phi(k)*x^k/(1 - x^k) and phi() is the Euler totient function (A000010). - Ilya Gutkovskiy, Aug 31 2017 MAPLE a:=n->add(ilcm( n, j ), j=1..n): seq(a(n), n=1..50); # Zerinvary Lajos, Nov 07 2006 MATHEMATICA Table[Sum[LCM[k, n], {k, 1, n}], {n, 1, 39}] (* Geoffrey Critzer, Feb 16 2015 *) PROG (Haskell) a051193 = sum . a051173_row  -- Reinhard Zumkeller, Feb 11 2014 (PARI) a(n) = sum(k=1, n, lcm(n, k)); \\ Michel Marcus, Feb 06 2015 CROSSREFS Cf. A000010, A051173 (triangle whose n-th row sum is a(n)). Sequence in context: A037338 A136486 A003203 * A216244 A215223 A318610 Adjacent sequences:  A051190 A051191 A051192 * A051194 A051195 A051196 KEYWORD nonn AUTHOR 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 October 15 15:14 EDT 2019. Contains 328030 sequences. (Running on oeis4.)