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Search: id:A077854
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| A077854 |
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Expansion of 1/((1-x)*(1-2*x)*(1+x^2)). |
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+0
4
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| 1, 3, 6, 12, 25, 51, 102, 204, 409, 819, 1638, 3276, 6553, 13107, 26214, 52428, 104857, 209715, 419430, 838860, 1677721, 3355443, 6710886, 13421772, 26843545, 53687091, 107374182, 214748364, 429496729, 858993459, 1717986918, 3435973836, 6871947673
(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) = 3*a(n-1)-3*a(n-2)+3*a(n-3)-2*a(n-4), with initial values 1 3 6 12.
(1/10) {2^(n+4) + (-1)^[n/2] - 2(-1)^[(n+1)/2] - 5}.
Row sums of A130306. - Gary W. Adamson (qntmpkt(AT)yahoo.com), May 20 2007
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MAPLE
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a := proc(n) option remember; if n=0 then RETURN(1); fi; if n=1 then RETURN(3); fi; if n=2 then RETURN(6); fi; if n=3 then RETURN(12); fi; 3*a(n-1)-3*a(n-2)+3*a(n-3)-2*a(n-4); end;
seq(iquo(2^n, 5), n=3..35); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 20 2008
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CROSSREFS
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Equals A007909(n+3) - [n congruent 2, 3 mod 4].
Cf. A130306.
Sequence in context: A088970 A068425 A136444 this_sequence A099445 A004067 A092886
Adjacent sequences: A077851 A077852 A077853 this_sequence A077855 A077856 A077857
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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), Nov 17 2002
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