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Search: id:A011377
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| A011377 |
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Expansion of 1/(1-x)*(1-2*x)*(1-x^2). |
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+0
7
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| 1, 3, 8, 18, 39, 81, 166, 336, 677, 1359, 2724, 5454, 10915, 21837, 43682, 87372, 174753, 349515, 699040, 1398090, 2796191, 5592393, 11184798, 22369608, 44739229, 89478471, 178956956, 357913926
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=sum{k=0..n+2, floor((n-k+2)/2)2^k}=sum{k=0..n+2, floor(k/2)2^(n-k+2)} - Paul Barry (pbarry(AT)wit.ie), Jul 29 2004
a(n)=sum{k=0..floor((n+2)/2), binomial(n-k+2, k+2)2^k} - Paul Barry (pbarry(AT)wit.ie), Oct 25 2004
a(n) = [(2^(n+4)-3n-6)/6] - David W. Wilson, Feb 26 2006
a(n) = (2^(n+5)-6n-21+(-1)^n)/12 - Hieronymus Fischer (Hieronymus.Fischer(AT)gmx.de), Dec 02 2006
Row sums of triangle A135086 - Gary W. Adamson (qntmpkt(AT)yahoo.com), Nov 18 2007
a(n)=3a(n-1)-a(n-2)-3a(n-3)+2a(n-4). - Paul Curtz (bpcrtz(AT)free.fr), Jul 29 2008
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CROSSREFS
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Partial sums of A000975. Second partial sums of A001045.
Cf. A135086.
Sequence in context: A117727 A117713 A128552 this_sequence A036385 A026635 A135094
Adjacent sequences: A011374 A011375 A011376 this_sequence A011378 A011379 A011380
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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