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!)
A332889 a(n) = number of strict partition numbers >1 that are proper divisors of the n-th strict partition number. 1

%I #4 Mar 11 2020 21:27:19

%S 0,0,0,1,0,2,2,2,4,2,3,1,1,3,1,1,5,4,3,0,3,1,1,3,8,3,5,3,4,6,5,6,3,2,

%T 7,10,1,1,9,2,4,3,7,11,3,6,9,1,0,1,9,3,3,2,1,6,11,8,2,1,7,2,6,2,4,12,

%U 3,0,4,8,4,4,1,7,0,1,9,7,5,5,1,1,6,5,4

%N a(n) = number of strict partition numbers >1 that are proper divisors of the n-th strict partition number.

%C Let p(n) = number of strict partitions of n. Then p(11) = 12, which is divisible by these 6 strict partition numbers: p(2) = 1, p(3) = 2, p(5) = 3, p(6) = 4, p(8) = 6, and p(11) = 12; discounting 1 and 12 leaves a(11) = 4 divisors.

%F a(n) = A332888(n) - 2 for n >= 3.

%t p[n_] := PartitionsQ[n]; t[n_] := Table[p[k], {k, 0, n}]

%t -2+Table[Length[Intersection[t[n], Divisors[p[n]]]], {n, 3, 130}]

%Y Cf. A000009 (strict partition numbers), A322887, A332888.

%K nonn

%O 3,6

%A _Clark Kimberling_, Mar 11 2020

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 24 20:08 EDT 2024. Contains 371963 sequences. (Running on oeis4.)