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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
OFFSET
0,1
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]
LinearRecurrence[{4, 5}, {2, 2, 22}, 30] (* Harvey P. Dale, Oct 23 2024 *)
CROSSREFS
Sequence in context: A118454 A118326 A212847 * A357244 A001012 A040082
KEYWORD
easy,nonn,changed
AUTHOR
Mario Catalani (mario.catalani(AT)unito.it), Sep 01 2003
STATUS
approved