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!)
A316271 FDH numbers of strict non-knapsack partitions. 6

%I #4 Jun 29 2018 11:35:46

%S 24,40,70,84,120,126,135,168,198,210,216,220,231,264,270,280,286,312,

%T 330,351,360,364,378,384,408,416,420,440,456,462,504,520,528,540,544,

%U 546,552,560,576,594,600,616,630,640,646,660,663,680,696,702,728,744,748

%N FDH numbers of strict non-knapsack partitions.

%C A strict integer partition is knapsack if every subset has a different sum.

%C Let f(n) = A050376(n) be the n-th Fermi-Dirac prime. The FDH number of a strict integer partition (y_1,...,y_k) is f(y_1)*...*f(y_k).

%e a(1) = 24 is the FDH number of (3,2,1), which is not knapsack because 3 = 2 + 1.

%t nn=1000;

%t sksQ[ptn_]:=And[UnsameQ@@ptn,UnsameQ@@Plus@@@Union[Subsets[ptn]]];

%t FDfactor[n_]:=If[n==1,{},Sort[Join@@Cases[FactorInteger[n],{p_,k_}:>Power[p,Cases[Position[IntegerDigits[k,2]//Reverse,1],{m_}->2^(m-1)]]]]];

%t FDprimeList=Array[FDfactor,nn,1,Union];FDrules=MapIndexed[(#1->#2[[1]])&,FDprimeList];

%t Select[Range[nn],!sksQ[FDfactor[#]/.FDrules]&]

%Y Cf. A000712, A005117, A050376, A056239, A064547, A108917, A213925, A275972, A284640, A299702, A299755, A299757, A301899, A301900.

%K nonn

%O 1,1

%A _Gus Wiseman_, Jun 28 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 July 22 10:58 EDT 2024. Contains 374490 sequences. (Running on oeis4.)