This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A180235 #7 Jun 02 2025 03:03:12
%S A180235 0,0,2,1,2,3,3,4,5,6,8,10,12,15,19,23,29,36,44,55,68,84,104,128,158,
%T A180235 195,241,297,367,453,559,690,851,1050,1296,1599,1973,2434,3003,3705,
%U A180235 4571,5640,6958,8585,10592,13068,16123,19892,24542,30279,37357,46089,56863
%N A180235 Demi-tribonacci numbers (rounding up): a(0)=a(1)=0, a(2)=2; a(n) = ceiling( (a(n-1)+a(n-2)+a(n-3))/2 ).
%F A180235 a(0)=a(1)=0, a(2)=2; a(n) = ceiling( (a(n-1)+a(n-2)+a(n-3))/2 )
%F A180235 For n>5, a(n)=A180234(n+4)-1
%F A180235 a(n)/a(n-1) tends to 1.233751928528... which is a root of 2*x^3 - x^2 - x - 1 = 0
%t A180235 RecurrenceTable[{a[0]==a[1]==0,a[2]==2,a[n]==Ceiling[(a[n-1]+a[n-2]+ a[n-3])/2]},a,{n,60}] (* _Harvey P. Dale_, Dec 03 2011 *)
%Y A180235 Cf. A000213, A180234
%K A180235 easy,nonn
%O A180235 0,3
%A A180235 _Carl R. White_, Aug 18 2010