A320700 Odd numbers whose product of prime indices is a nonprime prime power (A246547).

7, 9, 19, 21, 23, 25, 27, 49, 53, 57, 63, 81, 97, 103, 115, 121, 125, 131, 133, 147, 159, 171, 189, 227, 243, 289, 311, 343, 361, 371, 393, 399, 419, 441, 477, 513, 515, 529, 567, 575, 625, 661, 691, 719, 729, 917, 931, 933, 961, 1007, 1009, 1029, 1067, 1083

Offset

1,1

Links

Table of n, a(n) for n=1..54.

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), (8), (4,2), (9), (3,3), (2,2,2), (4,4), (16), (8,2), (4,2,2), (2,2,2,2), (25), (27), (9,3), (5,5), (3,3,3), (32), (8,4), (4,4,2), (16,2), (8,2,2), (4,2,2,2), (49), (2,2,2,2,2)

Mathematica

Select[Range[1000], With[{x=Times@@Cases[FactorInteger[#], {p_, k_}:>PrimePi[p]^k]}, OddQ[#]&&!PrimeQ[x]&&PrimePowerQ[x]]&]

Crossrefs

Cf. A000720, A000961, A001597, A003963, A056239, A064573, A112798, A246547, A279787, A320322, A320325, A320698, A320699.

Sequence in context: A256613 A116484 A138749 * A053803 A320323 A032791

Adjacent sequences: A320697 A320698 A320699 * A320701 A320702 A320703

Keyword

nonn

Author

Gus Wiseman, Oct 19 2018

Status

approved