A320699 Numbers whose product of prime indices is a nonprime prime power (A246547).

7, 9, 14, 18, 19, 21, 23, 25, 27, 28, 36, 38, 42, 46, 49, 50, 53, 54, 56, 57, 63, 72, 76, 81, 84, 92, 97, 98, 100, 103, 106, 108, 112, 114, 115, 121, 125, 126, 131, 133, 144, 147, 152, 159, 162, 168, 171, 184, 189, 194, 196, 200, 206, 212, 216, 224, 227, 228

Offset

1,1

Comments

First differs from A320325 at a(43) = 152, A320325(43) = 151.

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

Table of n, a(n) for n=1..58.

Index entries for sequences computed from indices in prime factorization

Example

The sequence of all integer partitions whose Heinz numbers belong to the sequence begins: (4), (2,2), (4,1), (2,2,1), (8), (4,2), (9), (3,3), (2,2,2), (4,1,1), (2,2,1,1), (8,1), (4,2,1), (9,1), (4,4), (3,3,1), (16), (2,2,2,1), (4,1,1,1), (8,2), (4,2,2), (2,2,1,1,1), (8,1,1), (2,2,2,2), (4,2,1,1), (9,1,1), (25), (4,4,1), (3,3,1,1).

Mathematica

Select[Range[100], With[{x=Times@@Cases[FactorInteger[#], {p_, k_}:>PrimePi[p]^k]}, !PrimeQ[x]&&PrimePowerQ[x]]&]

Crossrefs

Cf. A000720, A000961, A001597, A003963, A056239, A064573, A112798, A246547, A246655, A279787, A320322, A320325, A320698, A320700.

Sequence in context: A116025 A344011 A320325 * A332514 A353168 A305214

Adjacent sequences: A320696 A320697 A320698 * A320700 A320701 A320702

Keyword

nonn

Author

Gus Wiseman, Oct 19 2018

Status

approved