A325460 - OEIS

A325460

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

1, 2, 3, 5, 7, 10, 11, 13, 14, 17, 19, 22, 23, 26, 29, 31, 33, 34, 37, 38, 39, 41, 43, 46, 47, 51, 53, 57, 58, 59, 61, 62, 67, 69, 71, 73, 74, 79, 82, 83, 85, 86, 87, 89, 93, 94, 95, 97, 101, 103, 106, 107, 109, 111, 113, 115, 118, 122, 123, 127, 129, 130, 131

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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 (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 A179269.

LINKS

Table of n, a(n) for n=1..63.

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}

7: {4}

10: {1,3}

11: {5}

13: {6}

14: {1,4}

17: {7}

19: {8}

22: {1,5}

23: {9}

26: {1,6}

29: {10}

31: {11}

33: {2,5}

34: {1,7}

37: {12}

38: {1,8}

MATHEMATICA

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

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

CROSSREFS

A subsequence of A005117.

Cf. A007294, A056239, A112798, A179269, A325327, A325362, A325364, A325367, A325388, A325390, A325395, A325398, A325456, A325461.

Sequence in context: A325160 A258613 A392707 * A002269 A327445 A325119

Adjacent sequences: A325457 A325458 A325459 * A325461 A325462 A325463

KEYWORD

nonn

AUTHOR

Gus Wiseman, May 03 2019

STATUS

approved