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A049876
a(n)=Sum{a(k): k=0,1,2,...,n-4,n-2,n-1}; a(n-3) is not a summand; 3 initial terms required.
0
2, 3, 4, 7, 13, 25, 47, 88, 164, 306, 571, 1066, 1990, 3715, 6935, 12946, 24167, 45114, 84217, 157213, 293479, 547855, 1022714, 1909162, 3563948, 6653037, 12419626, 23184466, 43279843, 80793097, 150821354, 281547331, 525581408
OFFSET
0,1
FORMULA
a(n)=2*a(n-1)-a(n-3)+a(n-4); 4 initial terms required.
MATHEMATICA
LinearRecurrence[{2 , 0, -1, 1}, {2, 3, 4, 7}, 40] (* Harvey P. Dale, May 02 2012 *)
CROSSREFS
Sequence in context: A099779 A270440 A000690 * A049795 A329111 A014251
KEYWORD
nonn
STATUS
approved