The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
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!)
A325366 Heinz numbers of integer partitions whose augmented differences are distinct. 19

%I #7 Apr 07 2021 12:22:44

%S 1,2,3,5,6,7,9,10,11,13,14,17,19,21,22,23,25,26,29,31,33,34,35,37,38,

%T 39,41,42,43,46,47,49,51,53,57,58,59,61,62,63,65,66,67,69,70,71,73,74,

%U 77,78,79,82,83,85,86,87,89,91,93,94,95,97,99,101,102,103

%N Heinz numbers of integer partitions whose augmented differences are distinct.

%C The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

%C The augmented differences aug(y) of an integer partition y of length k are given by aug(y)_i = y_i - y_{i + 1} + 1 if i < k and aug(y)_k = y_k. For example, aug(6,5,5,3,3,3) = (2,1,3,1,1,3).

%C The enumeration of these partitions by sum is given by A325349.

%H Gus Wiseman, <a href="/A325325/a325325.txt">Sequences counting and ranking integer partitions by the differences of their successive parts.</a>

%e The sequence of terms together with their prime indices begins:

%e 1: {}

%e 2: {1}

%e 3: {2}

%e 5: {3}

%e 6: {1,2}

%e 7: {4}

%e 9: {2,2}

%e 10: {1,3}

%e 11: {5}

%e 13: {6}

%e 14: {1,4}

%e 17: {7}

%e 19: {8}

%e 21: {2,4}

%e 22: {1,5}

%e 23: {9}

%e 25: {3,3}

%e 26: {1,6}

%e 29: {10}

%e 31: {11}

%t primeptn[n_]:=If[n==1,{},Reverse[Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]]];

%t aug[y_]:=Table[If[i<Length[y],y[[i]]-y[[i+1]]+1,y[[i]]],{i,Length[y]}];

%t Select[Range[100],UnsameQ@@aug[primeptn[#]]&]

%Y Positions of squarefree numbers in A325351.

%Y Cf. A056239, A093641, A112798, A130091, A325349, A325355, A325367, A325368, A325389, A325394, A325395, A325396, A325405.

%K nonn

%O 1,2

%A _Gus Wiseman_, May 02 2019

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 June 9 21:45 EDT 2024. Contains 373248 sequences. (Running on oeis4.)