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A085155 Powers of semiprimes. 7
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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

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

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 *)

PROG

(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

CROSSREFS

Semiprime analog of A000961 = prime powers.

Cf. A001358, A074985, A085156.

Sequence in context: A300079 A233182 A028260 * A219786 A302038 A063762

Adjacent sequences:  A085152 A085153 A085154 * A085156 A085157 A085158

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jun 21 2003

STATUS

approved

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Last modified February 20 17:04 EST 2020. Contains 332080 sequences. (Running on oeis4.)