A325368 - OEIS

A325368

Heinz numbers of integer partitions with distinct differences between successive parts.

1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 25, 26, 28, 29, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 82, 83

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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 enumeration of these partitions by sum is given by A325325.

LINKS

Table of n, a(n) for n=1..67.

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

EXAMPLE

Most small numbers are in the sequence, but the sequence of non-terms together with their prime indices begins:

8: {1,1,1}

16: {1,1,1,1}

24: {1,1,1,2}

27: {2,2,2}

30: {1,2,3}

32: {1,1,1,1,1}

36: {1,1,2,2}

40: {1,1,1,3}

48: {1,1,1,1,2}

54: {1,2,2,2}

56: {1,1,1,4}

60: {1,1,2,3}

64: {1,1,1,1,1,1}

72: {1,1,1,2,2}

80: {1,1,1,1,3}

81: {2,2,2,2}

88: {1,1,1,5}

90: {1,2,2,3}

96: {1,1,1,1,1,2}

100: {1,1,3,3}

MATHEMATICA

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

Select[Range[100], UnsameQ@@Differences[primeptn[#]]&]

CROSSREFS

Cf. A056239, A112798, A130091, A240026, A325325, A325328, A325352, A325360, A325361, A325366, A325367, A325405, A325456, A325457.

Sequence in context: A048107 A342521 A078129 * A325251 A330977 A188437

Adjacent sequences: A325365 A325366 A325367 * A325369 A325370 A325371

KEYWORD

nonn

AUTHOR

Gus Wiseman, May 02 2019

STATUS

approved