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!)
A101510 Diagonal sums of binomial-Möbius product. 3

%I #35 Mar 19 2019 04:17:11

%S 1,2,5,10,21,43,87,175,352,707,1417,2836,5674,11353,22716,45443,90886,

%T 181748,363451,726870,1453773,2907648,5815315,11630195,23259059,

%U 46515887,93029852,186060921,372129424,744272221,1488552317,2977079872

%N Diagonal sums of binomial-Möbius product.

%C Diagonal sums of A101508.

%H Seiichi Manyama, <a href="/A101510/b101510.txt">Table of n, a(n) for n = 0..500</a>

%F a(n) = Sum_{k=0..floor(n/2)} Sum_{i=0..n-k, (k+1)|(i+1)} binomial(n-k,i).

%F G.f.: (1/x^2) * Sum_{n>=1} a*z^n/(1-a*z^n) (generalized Lambert series) where z=x/(1-x) and a=x. - _Joerg Arndt_, Jan 30 2011

%F a(n) ~ log(2) * 2^(n+1). - _Vaclav Kotesovec_, Mar 18 2019

%t a[n_] := Sum[If[Mod[i+1, k+1] == 0, Binomial[n-k, i], 0], {k, 0, n/2}, {i, 0, n-k}]; Table[a[n], {n, 0, 31}] (* _Jean-François Alcover_, Jan 24 2014 *)

%t nmax = 40; CoefficientList[Series[(1/x^2) * Sum[x*(x/(1-x))^k/(1-x*(x/(1-x))^k), {k, 1, nmax}], {x, 0, nmax}], x] (* _Vaclav Kotesovec_, Mar 18 2019 *)

%o (PARI) a(n) = sum(k=0, n\2, sum(i=0, n-k, if (!Mod(i+1, k+1), binomial(n-k, i)))); \\ _Michel Marcus_, Mar 16 2019

%K easy,nonn

%O 0,2

%A _Paul Barry_, Dec 05 2004

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 28 10:31 EDT 2024. Contains 371240 sequences. (Running on oeis4.)