The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A051307 Number of 7-element proper antichains of an n-element set. 2

%I

%S 0,0,0,0,0,135,329205,365924948,205640068950,75013516525425,

%T 20611869786684495,4661763066154503606,917701003163074793520,

%U 163180081989646991509955,26889766005753182579964345,4182467653250525215771670424,622388054953695081193665509610

%N Number of 7-element proper antichains of an n-element set.

%F a(n) = 1/7! * (128^n -63*96^n +525*80^n -315*72^n +1785*68^n -1386*66^n +455*65^n -3486*64^n -9450*60^n +21315*56^n +8505*54^n -13650*52^n -5355*51^n +36750*50^n -5145*49^n -14805*48^n -57960*46^n -4725*45^n +45738*44^n +36120*43^n -191835*42^n +43050*41^n +74725*40^n -73710*39^n +333165*38^n +104895*37^n -73395*36^n -54390*35^n -354144*34^n -423192*33^n +383621*32^n +143220*31^n -292425*30^n +753855*29^n +181545*28^n -314685*27^n -114660*26^n -916125*25^n -268716*24^n +1998493*23^n +140833*22^n -2359350*21^n +458675*20^n +2147950*19^n -961758*18^n -1428000*17^n +933380*16^n +578175*15^n -614362*14^n +143052*13^n +45990*12^n -244860*11^n +356475*10^n -199521*9^n -12244*8^n +64778*7^n -40026*6^n +28035*5^n -9604*4^n -5292*3^n +4248*2^n -720).

%Y Cf. A032263, A036239, A051112.

%K nonn

%O 0,6

%A _Vladeta Jovovic_, Goran Kilibarda, Zoran Maksimovic

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 24 17:52 EDT 2023. Contains 361505 sequences. (Running on oeis4.)