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%I #6 May 09 2013 22:45:33
%S 0,1,1,3,10,91,5151,13741903,94490753712985,
%T 4464252567106907867941273716,
%U 9964775491460730298984873904585383048580645394630925051
%N a(n) = triangular(a(n-1)+a(n-2)) if n > 1, else a(n) = n.
%o (Python)
%o prpr, prev = 0, 1
%o for i in range(1, 17):
%o print str(prpr)+',',
%o n = prpr+prev
%o cur = n*(n+1)/2
%o prpr, prev = prev, cur
%Y Cf. A000217, A072638.
%K nonn
%O 0,4
%A _Alex Ratushnyak_, May 09 2013
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