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!)
A284836 Expansion of Sum_{i>=1} x^(i^2)/(1 - x^(i^2)) * Product_{j=1..i} 1/(1 - x^(j^2)). 0

%I #7 Apr 05 2017 04:47:25

%S 1,2,3,5,6,7,8,11,13,14,15,19,21,22,23,29,31,34,35,42,44,47,48,56,60,

%T 63,67,76,80,83,87,99,103,108,112,130,134,139,143,162,169,174,180,200,

%U 213,218,224,248,262,272,278,306,320,337,343,372,390,408,419,449,471,489,508,544,567,591,611,654,677,705

%N Expansion of Sum_{i>=1} x^(i^2)/(1 - x^(i^2)) * Product_{j=1..i} 1/(1 - x^(j^2)).

%C Total number of largest parts in all partitions of n into squares (A000290).

%H <a href="/index/Par#partN">Index entries for related partition-counting sequences</a>

%F G.f.: Sum_{i>=1} x^(i^2)/(1 - x^(i^2)) * Product_{j=1..i} 1/(1 - x^(j^2)).

%e a(9) = 13 because we have [9], [4, 4, 1], [4, 1, 1, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1, 1] and 1 + 2 + 1 + 9 = 13.

%t nmax = 70; Rest[CoefficientList[Series[Sum[x^i^2/(1 - x^i^2) Product[1/(1 - x^j^2), {j, 1, i}], {i, 1, nmax}], {x, 0, nmax}], x]]

%o (PARI) x='x+O('x^71); Vec(sum(i=1, 71, x^(i^2)/(1 - x^(i^2)) * prod(j=1, i, 1/(1 - x^(j^2))))) \\ _Indranil Ghosh_, Apr 04 2017

%Y Cf. A000290, A001156, A046746, A092311, A281541, A284830.

%K nonn

%O 1,2

%A _Ilya Gutkovskiy_, Apr 03 2017

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 April 19 07:38 EDT 2024. Contains 371782 sequences. (Running on oeis4.)