# [seqfan] Re: Help with A002793 needed/Karol A. Penson

Christopher Gribble chris.eveswell at virgin.net
Mon Jul 5 19:11:16 CEST 2010

```Hi Karol,

The formula for A002793 is in the title for the sequence, namely:

a(n) = 2n * a(n-1) - (n-1)^2 * a(n-2)

Best regards,

Chris Gribble

-----Original Message-----
From: seqfan-bounces at list.seqfan.eu [mailto:seqfan-bounces at list.seqfan.eu]
On Behalf Of Karol PENSON
Sent: 05 July 2010 6:02 PM
To: Sequence Fanatics Discussion list; Karol
Subject: [seqfan] Help with A002793 needed/Karol A. Penson

Can anyone help with the following three questions concerning A002793:

1.  is the formula for a(n) known ?
2.  is any generating function (ogf , egf ... etc. ) of a(n) known ?
3.  in one of my calculations the following splitting of a(n)'s
appear :

a(2)=4    =3+1
a(3)=20  =11+8+1
a(4)=124=50+58+15+1
a(5)=920=274+444+177+24+1,
etc.
I would be happy to obtain the formula for the triangle.

Thanks in advance ,    Karol A. Penson

_______________________________________________

Seqfan Mailing list - http://list.seqfan.eu/

```

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