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A139149 a(n) = (n!+2)/2. 2
2, 4, 13, 61, 361, 2521, 20161, 181441, 1814401, 19958401, 239500801, 3113510401, 43589145601, 653837184001, 10461394944001, 177843714048001, 3201186852864001, 60822550204416001, 1216451004088320001, 25545471085854720001, 562000363888803840001 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
Also the number of (not necessarily maximal) cliques in the (n-1)-(weak) Bruhat graph. - Eric W. Weisstein, Jul 29 2018
LINKS
Eric Weisstein's World of Mathematics, Bruhat Graph
Eric Weisstein's World of Mathematics, Clique
EXAMPLE
(1!+2)/2 = 3/2 is not an integer, a(2) = (2!+2)/2 = 2.
MATHEMATICA
Table[(n! + 2)/2, {n, 2, 30}]
PROG
(PARI) a(n)=n!/2+1 \\ Charles R Greathouse IV, Jun 20 2012
CROSSREFS
Numbers of the form (n!+m)/m:
m=1 numbers of the form (n!+1)/1 see A038507
m=2 (this sequence)
m=3 numbers of the form (n!+3)/3 see A139150
m=4 numbers of the form (n!+4)/4 see A139151
m=5 numbers of the form (n!+5)/5 see A139152
m=6 numbers of the form (n!+6)/6 see A139153
m=7 numbers of the form (n!+7)/7 see A139154
m=8 numbers of the form (n!+8)/8 see A139155
m=9 numbers of the form (n!+9)/9 see A139156
m=10 numbers of the form (n!+10)/10 see A139157
Offsets for above sequences are Kempner numbers A002034.
For smallest number of the form (m!+n)/n see A139148.
Sequence in context: A201691 A020120 A020097 * A297861 A298128 A132786
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Apr 11 2008
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)