A107031 - OEIS

A107031

Diagonal sums of number triangle A107030.

1, 2, 3, 4, 7, 12, 25, 56, 145, 422, 1389, 5072, 20283, 87996, 412663, 2087868, 11361831, 66155642, 409567833, 2680486870, 18465061963, 133504614880, 1011121118741, 8008145020804, 66201411633209, 570006877641976

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..25.

FORMULA

a(n)=sum{k=0..floor(n/2), (k-1)*C(k(n-2k), n-2k)-(k-2)*sum{j=0..n-k, C(k(n-2k), j)}}

CROSSREFS

Sequence in context: A194079 A124390 A215981 * A207573 A152605 A285222

Adjacent sequences: A107028 A107029 A107030 * A107032 A107033 A107034

KEYWORD

easy,nonn

AUTHOR

Paul Barry, May 09 2005

STATUS

approved