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A082130 2*n-1 and 2*n+1 are semiprimes. 3
17, 25, 28, 43, 46, 47, 60, 61, 71, 72, 80, 92, 93, 101, 102, 107, 108, 109, 110, 118, 124, 133, 144, 145, 150, 151, 152, 160, 161, 164, 170, 196, 197, 206, 207, 208, 223, 226, 235, 236, 258, 259, 264, 267, 268, 272, 276, 290, 291, 295 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

EXAMPLE

a(1)=17 because 2*17-1=33=3*11 and 2*17+1=35=5*7 are both semiprimes.

CROSSREFS

Cf. A001358, A082131.

Sequence in context: A051780 A124971 A105448 * A140609 A131275 A183346

Adjacent sequences:  A082127 A082128 A082129 * A082131 A082132 A082133

KEYWORD

nonn

AUTHOR

Hugo Pfoertner (hugo(AT)pfoertner.org), Apr 04 2003

EXTENSIONS

More terms from Jud McCranie, Apr 04 2003

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Last modified February 14 04:29 EST 2012. Contains 205570 sequences.