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Main diagonal of A099239.
2

%I #9 Mar 09 2021 07:33:16

%S 1,2,8,41,250,1757,13917,122166,1173662,12222605,136927351,1639768418,

%T 20880556880,281460326864,4000651782511,59761935358025,

%U 935445106491702,15303039199768237,261030618751031385,4632889302298054713

%N Main diagonal of A099239.

%H G. C. Greubel, <a href="/A099240/b099240.txt">Table of n, a(n) for n = 0..490</a>

%F a(n) = Sum_{j=0..n} binomial(n^2 - (n-1)*(j-1), j).

%F a(n) = Sum_{j=0..n} binomial(n + (n-1)*(j+1), n*(j+1) - 1) with a(0) = 1.

%t Table[Sum[Binomial[n^2 -(n-1)*(j-1), j], {j,0,n}], {n,0,30}] (* _G. C. Greubel_, Mar 09 2021 *)

%o (Sage) [sum(binomial(n^2 -(n-1)*(j-1), j) for j in (0..n)) for n in (0..30)] # _G. C. Greubel_, Mar 09 2021

%o (Magma) [1] cat [(&+[Binomial(n+(n-1)*(j+1), n*(j+1)-1): j in [0..n]]): n in [1..30]]; // _G. C. Greubel_, Mar 09 2021

%Y Cf. A099239.

%K easy,nonn

%O 0,2

%A _Paul Barry_, Oct 08 2004