cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A325135 Size of the integer partition with Heinz number n after its inner lining, or, equivalently, its largest hook, is removed.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 2, 0, 2, 0, 0, 1, 0, 0, 1, 0, 2, 1, 0, 0, 1, 0, 0, 1, 0, 0, 2, 0, 0, 0, 3, 2, 1, 0, 0, 2, 2, 0, 1, 0, 0, 1, 0, 0, 2, 0, 2, 1, 0, 0, 1, 2, 0, 1, 0, 0, 3, 0, 3, 1, 0, 0, 3, 0, 0, 1, 2, 0, 1, 0, 0, 2, 3, 0, 1, 0, 2, 0, 0, 3, 2, 2, 0, 1, 0, 0, 3
Offset: 1

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Author

Gus Wiseman, Apr 02 2019

Keywords

Comments

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

Examples

			The partition with Heinz number 715 is (6,5,3), with diagram
  o o o o o o
  o o o o o
  o o o
which has inner lining
          o o
      o o o
  o o o
or largest hook
  o o o o o o
  o
  o
both of which have complement
  o o o o
  o o
which has size 6, so a(715) = 6.
		

Crossrefs

Programs

  • Mathematica
    Table[If[n==1,0,Total[Most[Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]]-1]],{n,100}]
  • PARI
    A056239(n) = { my(f); if(1==n, 0, f=factor(n); sum(i=1, #f~, f[i,2] * primepi(f[i,1]))); }
    A061395(n) = if(1==n, 0, primepi(vecmax(factor(n)[, 1])));
    A325135(n) = if(1==n,0,(1+A056239(n)-bigomega(n)-A061395(n))); \\ Antti Karttunen, Apr 14 2019

Formula

a(n) = A056239(A325133(n)).
For n > 1:
a(n) = A056239(n) - A001222(n) - A061395(n) + 1.
a(n) = A056239(n) - A252464(n).
a(n) = A056239(n) - A325134(n) + 1.

Extensions

More terms from Antti Karttunen, Apr 14 2019