A085155 Powers of semiprimes.

1, 4, 6, 9, 10, 14, 15, 16, 21, 22, 25, 26, 33, 34, 35, 36, 38, 39, 46, 49, 51, 55, 57, 58, 62, 64, 65, 69, 74, 77, 81, 82, 85, 86, 87, 91, 93, 94, 95, 100, 106, 111, 115, 118, 119, 121, 122, 123, 129, 133, 134, 141, 142, 143, 145, 146, 155, 158, 159, 161, 166

Offset: 1

Author

Reinhard Zumkeller, Jun 21 2003

Keywords

• nonn

Comments

Numbers of form A001358(i)^j;

m>1 is a term iff A067029(m)=A071178(m) and (A001221(m)=2 or A067029(m) is even).

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Semiprime analog of A000961 = prime powers.

Cf. A001358, A074985, A085156.

Programs

Mathematica

Select[Range@ 166, Function[n, Or[n == 1, And[Length@ # == 1, EvenQ@ First@ #], And[Length@ # == 2, SameQ @@ #]] &[FactorInteger[n][[All, -1]]]]] (* Michael De Vlieger, Mar 04 2017 *)

PARI

is(n)=my(f=factor(n)[,2]); #f==0 || (#f==2 && f[1]==f[2]) || (#f==1 && f[1]%2==0) \\ Charles R Greathouse IV, Oct 19 2015

Formula

{1} UNION {A001358 semiprimes} UNION {A074985 squares of semiprimes} UNION {cubes of semiprimes} UNION {4th powers of semiprimes} UNION ... - Jonathan Vos Post, Sep 06 2006