%I A117824
%S A117824 0,1,2,5,4,13,12,19,24,35,50,75,114,177,278,441,704,1129,1816,2927,4724,
%T A117824 7631,12334,19943,32254,52173,84402,136549,220924,357445,578340,935755,
%U A117824 1514064,2449787,3963818,6413571,10377354,16790889,27168206,43959057
%N A117824 a(0) = 0, a(1) = 1; for n >= 2, a(n) = a(n-1) + a(n-2) - (n-1) if that 
               number is positive and not already in the sequence, otherwise a(n) 
               = a(n-1) + a(n-2) + (n-1).
%p A117824 a[0]:=0: a[1]:=1: A:={0,1}: for n from 2 to 42 do if a[n-1]+a[n-2]-n+1>
               0 and member(a[n-1]+a[n-2]-n+1,A)=false then a[n]:=a[n-1]+a[n-2]-n+1: 
               A:=A union {a[n-1]+a[n-2]-n+1} else a[n]:=a[n-1]+a[n-2]+n-1: A:=A 
               union {a[n-1]+a[n-2]+n-1} fi: od: seq(a[n],n=0..42); - Emeric Deutsch 
               (deutsch(AT)duke.poly.edu), Apr 30 2006
%Y A117824 Cf. A079053, A005132, A117821, A117822, A117823.
%Y A117824 Sequence in context: A073122 A084410 A080067 this_sequence A122212 A102468 
               A079053
%Y A117824 Adjacent sequences: A117821 A117822 A117823 this_sequence A117825 A117826 
               A117827
%K A117824 nonn,easy
%O A117824 0,3
%A A117824 N. J. A. Sloane (njas(AT)research.att.com), Apr 30 2006
%E A117824 More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 30 2006