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A138495
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First differences of A138477.
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1
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0, 1, 1, 1, 3, 9, 15, 25, 55, 121, 231, 441, 903, 1829, 3655, 7225, 14535, 29241, 58311, 116281, 232903
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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FORMULA
| O.g.f.: x/((1-2x)(1+x)(1+2x^2)) . a(n) = a(n-1) +2a(n-3) +4a(n-4). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 19 2008
a(n)= -1/9*(-1)^n+2/9*2^n-1/18*(I*sqrt(2))^n-(1/9*I)*(I*sqrt(2))^n*sqrt(2)+(1/9*I) *sqrt(2)*(-I*sqrt(2))^n-1/18*(-I*sqrt(2))^n, with n>=0 and I=sqrt(-1) - Paolo P. Lava (paoloplava(AT)gmail.com), Jun 03 2008
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CROSSREFS
| Sequence in context: A192720 A099989 A085046 * A055927 A087031 A089632
Adjacent sequences: A138492 A138493 A138494 * A138496 A138497 A138498
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KEYWORD
| nonn
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), May 18 2008
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