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.

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A284609 Number of partitions of n such that the (sum of all odd parts) = floor(n/2).

Original entry on oeis.org

0, 0, 1, 1, 0, 0, 4, 4, 0, 0, 9, 12, 0, 0, 25, 30, 0, 0, 56, 70, 0, 0, 132, 165, 0, 0, 270, 330, 0, 0, 594, 704, 0, 0, 1140, 1380, 0, 0, 2268, 2688, 0, 0, 4256, 4984, 0, 0, 8008, 9394, 0, 0, 14342, 16665, 0, 0, 25920, 29970, 0, 0, 45056, 52096
Offset: 1

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Author

Clark Kimberling, Mar 30 2017

Keywords

Comments

Consequently the sum of all even parts is ceiling(n/2). Therefore, a(4n + 1) = a(4n + 2) = 0. - David A. Corneth, Apr 02 2017

Examples

			a(8) counts these 4 partitions: 431, 3221, 32111, 311111.
		

Crossrefs

Programs

  • Mathematica
    Table[p = IntegerPartitions[n];   Length[Select[
       Table[Total[Select[DeleteDuplicates[p[[k]]], EvenQ]], {k,
         Length[p]}], # == Floor[n/2] &]], {n, 60}] (* Peter J. C. Moses, Mar 29 2017 *)
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