|
| |
|
|
A098594
|
|
Numbers n such that n!-1 and n!+1 are both semiprime.
|
|
0
| | |
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| This sequence is formed of all those terms that appear in both A078778 and A078781.
No more terms < 307. - David Wasserman (dwasserm(AT)earthlink.net), Feb 26 2008
a(11) >= 464. [D. S. McNeil, Sep 4 2011]
|
|
|
EXAMPLE
| 10!+1 = 3628801 = 11*329891 and 10!-1 = 3628799 = 29*125131 so 10 is a member of the sequence.
|
|
|
MAPLE
| out:=[]: for n from 1 to 60 do: a:=n!-1: b:=n!+1: if (bigomega(a)=2) and (bigomega(b)=2) then out:=[op(out), n]: print(n): fi: od: out;
|
|
|
CROSSREFS
| Cf. A078778, A078781.
Sequence in context: A022158 A032717 A205676 * A154315 A022799 A196384
Adjacent sequences: A098591 A098592 A098593 * A098595 A098596 A098597
|
|
|
KEYWORD
| hard,more,nonn
|
|
|
AUTHOR
| Mark Hudson (mrmarkhudson(AT)hotmail.com), Sep 17 2004
|
|
|
EXTENSIONS
| a(10) from D. S. McNeil (mcneil(AT)hku.hk), Sep 04 2011
|
| |
|
|
