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A139149
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a(n) = (n!+2)/2.
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2
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2, 4, 13, 61, 361, 2521, 20161, 181441, 1814401, 19958401, 239500801, 3113510401, 43589145601, 653837184001, 10461394944001, 177843714048001, 3201186852864001, 60822550204416001, 1216451004088320001, 25545471085854720001, 562000363888803840001
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OFFSET
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2,1
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COMMENTS
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Also the number of (not necessarily maximal) cliques in the (n-1)-(weak) Bruhat graph. - Eric W. Weisstein, Jul 29 2018
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LINKS
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Eric Weisstein's World of Mathematics, Clique
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EXAMPLE
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(1!+2)/2 = 3/2 is not an integer, a(2) = (2!+2)/2 = 2.
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MATHEMATICA
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Table[(n! + 2)/2, {n, 2, 30}]
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PROG
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CROSSREFS
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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.
Cf. A082672, A089085, A089130, A117141, A007749, A139056-A139066, A020458, A139068, A137390, A139070-A139075, A139148, A139149, A139157, A139159-A139162.
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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