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A087405 First differences of A087404: a(n)=A087404(n)-A087404(n-1), a(0)=A087404(0). 0
2, 2, 22, 98, 502, 2498, 12502, 62498, 312502, 1562498, 7812502, 39062498, 195312502, 976562498, 4882812502, 24414062498, 122070312502, 610351562498, 3051757812502, 15258789062498, 76293945312502, 381469726562498 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..21.

FORMULA

G.f.: ((1-x)(2-4x))/(1-4x-5x^2). For n>0: a(n)=4*5^(n-1)+2(-1)^n

MATHEMATICA

CoefficientList[Series[((1 - x)(2 - 4x))/(1 - 4x - 5x^2), {x, 0, 25}], x]

CROSSREFS

Sequence in context: A118454 A118326 A212847 * A001012 A040082 A014358

Adjacent sequences:  A087402 A087403 A087404 * A087406 A087407 A087408

KEYWORD

easy,nonn

AUTHOR

Mario Catalani (mario.catalani(AT)unito.it), Sep 01 2003

STATUS

approved

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Last modified January 27 02:46 EST 2020. Contains 331291 sequences. (Running on oeis4.)