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A099235

A quadrisection of 1/(1-x-x^5).

1, 1, 5, 15, 45, 140, 431, 1326, 4085, 12580, 38740, 119305, 367411, 1131476, 3484490, 10730820, 33046585, 101770120, 313410816, 965178576, 2972359720, 9153665985, 28189589705, 86812537085, 267347509271, 823322219501

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OFFSET

0,3

COMMENTS

A row of A099233.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (1,4,6,4,1).

FORMULA

G.f.: 1/(1-x(1+x)^4); a(n)=sum{k=0..n, binomial(4(n-k), k)}; a(n)=a(n-1)+4a(n-2)+6a(n-3)+4a(n-4)+a(n-5); a(n)=A003520(4n).

MATHEMATICA

Take[CoefficientList[Series[1/(1-x-x^5), {x, 0, 100}], x], {1, -1, 4}] (* or *) LinearRecurrence[{1, 4, 6, 4, 1}, {1, 1, 5, 15, 45}, 30] (* Harvey P. Dale, Mar 06 2015 *)

CROSSREFS

Sequence in context: A084244 A005030 A200664 * A207096 A035069 A176611

Adjacent sequences: A099232 A099233 A099234 * A099236 A099237 A099238

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Oct 08 2004

STATUS

approved