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!)
A318604 Number of partitions of prime(n) into distinct parts not larger than prime(n-1). 1

%I #18 Nov 30 2020 16:19:45

%S 1,1,3,7,16,33,52,99,246,338,750,1255,1608,2585,5110,9782,12074,22240,

%T 32987,40024,70478,101693,173672,345837,483325,570076,789635,927404,

%U 1274113,3725322,5010683,7755766,8953854,18108385,20792118,31316304,46828022,61000699

%N Number of partitions of prime(n) into distinct parts not larger than prime(n-1).

%C The first prime number taken into consideration in the sequence is prime(2)=3, as 2 does not have a preceding prime.

%H Alois P. Heinz, <a href="/A318604/b318604.txt">Table of n, a(n) for n = 2..1000</a>

%e a(5) = 7: there are 7 partitions of prime(5) = 11 into distinct parts not larger than prime(4) = 7: [7,4], [7,3,1], [6,5], [6,4,1], [6,3,2], [5,4,2], [5,3,2,1].

%p b:= proc(n,i) option remember; (m-> `if`(m<n, 0, `if`(m=n, 1,

%p b(n, i-1)+b(n-i, min(n-i, i-1)))))(i*(i+1)/2)

%p end:

%p a:= n-> (p-> b(p(n), p(n-1)))(ithprime):

%p seq(a(n), n=2..50); # _Alois P. Heinz_, Aug 29 2018

%t b[n_, i_] := b[n, i] = Function[m, If[m < n, 0, If[m == n, 1, b[n, i - 1] + b[n - i, Min[n - i, i - 1]]]]][i(i+1)/2];

%t a[n_] := b[Prime[n], Prime[n - 1]];

%t a /@ Range[2, 50] (* _Jean-François Alcover_, Nov 30 2020, after _Alois P. Heinz_ *)

%K nonn

%O 2,3

%A _Pierandrea Formusa_, Aug 29 2018

%E a(26)-a(39) from _Alois P. Heinz_, Aug 29 2018

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 August 30 16:34 EDT 2024. Contains 375545 sequences. (Running on oeis4.)