A350949 - OEIS

A350949

Heinz numbers of integer partitions with as many even parts as even conjugate parts and as many odd parts as odd conjugate parts.

1, 2, 6, 9, 20, 30, 56, 75, 84, 125, 176, 210, 264, 294, 315, 350, 416, 441, 490, 525, 624, 660, 735, 924, 990, 1088, 1100, 1386, 1540, 1560, 1632, 1650, 1715, 2184, 2310, 2340, 2401, 2432, 2600, 3267, 3276, 3388, 3640, 3648, 3900, 4080, 4125, 5082, 5324, 5390

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OFFSET

1,2

COMMENTS

The Heinz number of a partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). This gives a bijective correspondence between positive integers and integer partitions.

LINKS

Table of n, a(n) for n=1..50.

FORMULA

Intersection of A350944 and A350945.

A257991(a(n)) = A344616(a(n)).

A257992(a(n)) = A350847(a(n)).

Closed under A122111 (conjugation).

EXAMPLE

The terms together with their prime indices begin:

1: ()

2: (1)

6: (2,1)

9: (2,2)

20: (3,1,1)

30: (3,2,1)

56: (4,1,1,1)

75: (3,3,2)

84: (4,2,1,1)

125: (3,3,3)

176: (5,1,1,1,1)

210: (4,3,2,1)

264: (5,2,1,1,1)

294: (4,4,2,1)

315: (4,3,2,2)

350: (4,3,3,1)

416: (6,1,1,1,1,1)

MATHEMATICA

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

conj[y_]:=If[Length[y]==0, y, Table[Length[Select[y, #>=k&]], {k, 1, Max[y]}]];

Select[Range[1000], Count[primeMS[#], _?OddQ]==Count[conj[primeMS[#]], _?OddQ]&&Count[primeMS[#], _?EvenQ]==Count[conj[primeMS[#]], _?EvenQ]&]

CROSSREFS

The second condition alone is A350944, counted by A277103.

The first condition alone is A350945, counted by A350948.

The case of all four statistics equal is A350947, counted by A351978.

These partitions are counted by A351976.

There are four other possible pairings of statistics:

- A045931: # even = # odd, ranked by A325698, strict A239241.

- A045931: # even conj = # odd conj, ranked by A350848, strict A352129.

- A277579: # even = # odd conj, ranked by A349157, strict A352131.

- A277579: # even conj = # odd, ranked by A350943, strict A352130.

There are two other possible double-pairings of statistics:

- A350946, counted by A351977.

- A351980, counted by A351981.

A056239 adds up prime indices, counted by A001222, row sums of A112798.

A122111 represents partition conjugation using Heinz numbers.

A195017 = # of even parts - # of odd parts.

A257991 counts odd parts, conjugate A344616.

A257992 counts even parts, conjugate A350847.

A316524 = alternating sum of prime indices.

Cf. A026424, A028260, A098123, A130780, A171966, A241638, A325700, A350849, A350941, A350942, A350950, A350951.

Sequence in context: A129233 A106529 A325040 * A088902 A265016 A279897

Adjacent sequences: A350946 A350947 A350948 * A350950 A350951 A350952

KEYWORD

nonn

AUTHOR

Gus Wiseman, Mar 14 2022

STATUS

approved