A325362 - OEIS

A325362

Heinz numbers of integer partitions whose differences (with the last part taken to be 0) are weakly increasing.

1, 2, 3, 5, 6, 7, 10, 11, 13, 14, 17, 19, 21, 22, 23, 26, 29, 30, 31, 33, 34, 37, 38, 39, 41, 42, 43, 46, 47, 51, 53, 57, 58, 59, 61, 62, 65, 66, 67, 69, 71, 73, 74, 78, 79, 82, 83, 85, 86, 87, 89, 93, 94, 95, 97, 101, 102, 103, 106, 107, 109, 110, 111, 113

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OFFSET

1,2

COMMENTS

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

The differences of a sequence are defined as if the sequence were increasing, so for example the differences of (x, y, z) are (y - x, z - y). We adhere to this standard for integer partitions also even though they are always weakly decreasing. For example, the differences of (6,3,1) (with the last part taken to be 0) are (-3,-2,-1).

The enumeration of these partitions by sum is given by A007294.

This sequence and A025487, considered as sets, are related by the partition conjugation function A122111(.), which maps the members of either set 1:1 onto the other set. - Peter Munn, Feb 10 2022

LINKS

Table of n, a(n) for n=1..64.

Gus Wiseman, Sequences counting and ranking integer partitions by the differences of their successive parts.

EXAMPLE

The sequence of terms together with their prime indices begins:

1: {}

2: {1}

3: {2}

5: {3}

6: {1,2}

7: {4}

10: {1,3}

11: {5}

13: {6}

14: {1,4}

17: {7}

19: {8}

21: {2,4}

22: {1,5}

23: {9}

26: {1,6}

29: {10}

30: {1,2,3}

31: {11}

33: {2,5}

MATHEMATICA

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

Select[Range[100], OrderedQ[Differences[Append[primeptn[#], 0]]]&]

CROSSREFS

Cf. A007294, A056239, A112798, A240026, A320348, A325327, A325360, A325364, A325367, A325390, A325394, A325400.

Related to A025487 via A122111.

Sequence in context: A377871 A327906 A333866 * A339563 A325396 A326533

Adjacent sequences: A325359 A325360 A325361 * A325363 A325364 A325365

KEYWORD

nonn

AUTHOR

Gus Wiseman, May 02 2019

STATUS

approved