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A300789 Heinz numbers of integer partitions whose Young diagram can be tiled by dominos. 6
1, 3, 4, 7, 9, 10, 12, 13, 16, 19, 21, 22, 25, 27, 28, 29, 34, 36, 37, 39, 40, 43, 46, 48, 49, 52, 53, 55, 57, 61, 62, 63, 64, 70, 71, 75, 76, 79, 81, 82, 84, 85, 87, 88, 89, 90, 91, 94, 100, 101, 107, 108, 111, 112, 113, 115, 116, 117, 118, 121, 129, 130, 131 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

This sequence is conjectured to be the Heinz numbers of integer partitions in which the odd parts appear as many times in even as in odd positions.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..20000

Solomon W. Golomb, Tiling with polyominoes, Journal of Combinatorial Theory, 1-2 (1966), 280-296.

Wikipedia, Domino tiling

EXAMPLE

Sequence of integer partitions whose Young diagram can be tiled by dominos begins: (), (2), (11), (4), (22), (31), (211), (6), (1111), (8), (42), (51), (33), (222), (411).

MAPLE

a:= proc(n) option remember; local k; for k from 1+

      `if`(n=1, 0, a(n-1)) while (l-> add(`if`(l[i]::odd,

       (-1)^i, 0), i=1..nops(l))<>0)(sort(map(i->

       numtheory[pi](i[1])$i[2], ifactors(k)[2]))) do od; k

    end:

seq(a(n), n=1..100);  # Alois P. Heinz, May 22 2018

MATHEMATICA

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

Select[Range[100], Total[(-1)^Flatten[Position[primeMS[#], _?OddQ]]]===0&] (* Conjectured *)

CROSSREFS

Cf. A000712, A000898, A001405, A004003, A045931, A097613, A099390, A299926, A300056, A300060, A300787, A300788, A304662.

Sequence in context: A213508 A088958 A300061 * A026225 A026140 A233010

Adjacent sequences:  A300786 A300787 A300788 * A300790 A300791 A300792

KEYWORD

nonn

AUTHOR

Gus Wiseman, Mar 12 2018

STATUS

approved

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Last modified April 2 19:05 EDT 2020. Contains 333190 sequences. (Running on oeis4.)