%I A047662
%S A047662 1,2,2,3,6,3,4,12,12,4,5,20,31,20,5,6,30,64,64,30,6,7,42,115,160,
%T A047662 115,42,7,8,56,188,340,340,188,56,8,9,72,287,644,841,644,287,72,
%U A047662 9,10,90,416,1120,1826,1826,1120,416,90,10,11,110,579,1824,3591
%N A047662 Square array a(n,k) read by antidiagonals: a(n,1)=n, a(1,k)=k, a(n,k)=a(n-1,
               k-1)+a(n-1,k)+a(n,k-1)+1.
%D A047662 M. L. Fredman, The complexity of maintaining an array and its partial 
               sums, J. Assoc. Comp. Machin., 29 (1982), 250-260.
%F A047662 a(n, k) =(A008288(n, k)-1)/2. Sum of antidiagonals is A048776.
%p A047662 A047662 := proc(n,k) option remember; if n = 1 then k; elif k = 1 then 
               n; else A047662(n-1,k-1)+A047662(n,k-1)+A047662(n-1,k)+1; fi; end;
%Y A047662 Rows give A037237, 4*A006007, A047661, A047663, A047664, main diagonal 
               is A047665 (see also A001850).
%Y A047662 Sequence in context: A128228 A125102 A003506 this_sequence A075196 A015050 
               A116447
%Y A047662 Adjacent sequences: A047659 A047660 A047661 this_sequence A047663 A047664 
               A047665
%K A047662 nonn,tabl,nice,easy
%O A047662 1,2
%A A047662 D. E. Knuth, N. J. A. Sloane (njas(AT)research.att.com).