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A180234
Demi-tribonacci numbers (rounding down): a(0)=a(1)=0, a(2)=2; a(n) = floor( (a(n-1)+a(n-2)+a(n-3))/2 )
1
0, 0, 2, 1, 1, 2, 2, 2, 3, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20, 24, 30, 37, 45, 56, 69, 85, 105, 129, 159, 196, 242, 298, 368, 454, 560, 691, 852, 1051, 1297, 1600, 1974, 2435, 3004, 3706, 4572, 5641, 6959, 8586, 10593, 13069, 16124, 19893, 24543, 30280, 37358, 46090
OFFSET
0,3
FORMULA
a(0)=a(1)=0, a(2)=2; a(n) = floor( (a(n-1)+a(n-2)+a(n-3))/2 )
For n>9, a(n)=A180235(n-4)+1
a(n)/a(n-1) tends to 1.233751928528... which is a root of 2*x^3 - x^2 - x - 1 = 0
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Carl R. White, Aug 18 2010
STATUS
approved