I haven't read the reference, but how's this? %S A005269 1,1,2,4,10,31,127,711,5621,64049,1067599,26287664,963023487, %T A005269 52766766100,4342736509018 %N A005269 a(n) = number of length-n sequences with s[1]=1, s[2]=1, s[k-1] <= s[k] <= s[k-2]+s[k-1] -- Don Reble djr at nk.ca