0,2

Diagonal sums of number triangle A117372.

a(n)=a(n-2)+a(n-3); a(n)=sum{k=0..floor(n/2), (-1)^n*(C(k,n-2k)+3*C(k, n-2k-1))}.

Sequence in context: A099813 A141300 A014388 this_sequence A021322 A036412 A016473

Adjacent sequences: A117371 A117372 A117373 this_sequence A117375 A117376 A117377

easy,sign

Paul Barry (pbarry(AT)wit.ie), Mar 10 2006