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A084075 Length of list created by n substitutions k -> Range[ -Abs[k+1],Abs[k-1],2] starting with {1}. 2
1, 2, 5, 12, 33, 86, 249, 680, 2033, 5722, 17485, 50260, 156033, 455534, 1431281, 4228752, 13412193, 40003058, 127840085, 384232156, 1235575201, 3737280582, 12080678505, 36736735672, 119276490193, 364372758986, 1187542872989 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..26.

FORMULA

invOGF=(-1-6n-8n^2+(1+2n)^2 Sqrt[1+4n])/(2(n+4n^2+4n^3))

EXAMPLE

{1}, {-2,0}, {-1,1,3,-1,1}, {0,2,-2,0,-4,-2,0,2,0,2,-2,0}

MATHEMATICA

Rest@CoefficientList[InverseSeries[Series[ (-1-6n-8n^2+(1+2n)^2 Sqrt[1+4n])/(2(n+4n^2+4n^3)), {n, 0, 28}]], n] or Length/@Flatten/@NestList[ #/.k_Integer:>Range[ -Abs[k+1], Abs[k-1], 2]&, {1}, 8]

CROSSREFS

a(2n-1)=A027307/2.

Sequence in context: A115523 A176336 A010843 * A209717 A000560 A292212

Adjacent sequences:  A084072 A084073 A084074 * A084076 A084077 A084078

KEYWORD

nonn

AUTHOR

Wouter Meeussen, May 11 2003

STATUS

approved

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Last modified March 21 21:34 EDT 2019. Contains 321382 sequences. (Running on oeis4.)