A371283 - OEIS

A371283

Heinz numbers of sets of divisors of positive integers. Numbers whose prime indices form the set of divisors of some positive integer.

2, 6, 10, 22, 34, 42, 62, 82, 118, 134, 166, 218, 230, 254, 314, 358, 382, 390, 422, 482, 554, 566, 662, 706, 734, 798, 802, 862, 922, 1018, 1094, 1126, 1174, 1198, 1234, 1418, 1478, 1546, 1594, 1718, 1754, 1838, 1914, 1934, 1982, 2062, 2126, 2134, 2174, 2306

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OFFSET

1,1

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.

A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.

LINKS

Joseph Likar, Table of n, a(n) for n = 1..10000

EXAMPLE

The terms together with their prime indices begin:

2: {1}

6: {1,2}

10: {1,3}

22: {1,5}

34: {1,7}

42: {1,2,4}

62: {1,11}

82: {1,13}

118: {1,17}

134: {1,19}

166: {1,23}

218: {1,29}

230: {1,3,9}

254: {1,31}

314: {1,37}

358: {1,41}

382: {1,43}

390: {1,2,3,6}

MATHEMATICA

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

Select[Range[2, 100], SameQ[prix[#], Divisors[Last[prix[#]]]]&]

CROSSREFS

Partitions of this type are counted by A054973.

The unsorted version is A275700.

These numbers have products A371286, unsorted version A371285.

Squarefree case of A371288, counted by A371284.

A000005 counts divisors.

A001221 counts distinct prime factors.

A027746 lists prime factors, A112798 indices, length A001222.

A355731 counts choices of a divisor of each prime index, firsts A355732.

A355741 counts choices of a prime factor of each prime index.

Cf. A000720, A005179, A007416, A034729, A370820, A371131, A371177.

Sequence in context: A080715 A034168 A055745 * A182000 A167512 A055895

Adjacent sequences: A371280 A371281 A371282 * A371284 A371285 A371286

KEYWORD

nonn

AUTHOR

Gus Wiseman, Mar 21 2024

STATUS

approved