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A077903
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Expansion of (1-x)^(-1)/(1+x-x^2+2*x^3).
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0
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1, 0, 2, -3, 6, -12, 25, -48, 98, -195, 390, -780, 1561, -3120, 6242, -12483, 24966, -49932, 99865, -199728, 399458, -798915, 1597830, -3195660, 6391321, -12782640, 25565282, -51130563, 102261126, -204522252, 409044505, -818089008, 1636178018, -3272356035, 6544712070
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Convolution of A010892(n) and (-1)^n*A001045(n+1). The positive sequence has g.f. 1/((1-x-2x^2)(1+x+x^2)). This is the convolution of A001045(n+1) and A049347(n). - Paul Barry (pbarry(AT)wit.ie), May 19 2004
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FORMULA
| G.f. : 1/((1+x-2x^2)(1-x+x^2)); a(n)=sum{k=0..n, (2*(-2)^k/3+1/3)2sin(pi*(n-k)/3+pi/3)/sqrt(3)}; a(n)=2^(n+3)cos(pi*n)/21+8sqrt(3)cos(pi*n/3+pi/6)/63+4sqrt(3)sin(pi*n/3+pi/3)/63 +2sqrt(3)sin(pi*n/3)/9+1/3; - Paul Barry (pbarry(AT)wit.ie), May 19 2004
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CROSSREFS
| Sequence in context: A035055 A119559 A045761 * A038086 A032305 A032218
Adjacent sequences: A077900 A077901 A077902 * A077904 A077905 A077906
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KEYWORD
| sign
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 17 2002
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