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A125176 Row sums of A125175. 5
1, 3, 7, 14, 28, 56, 112, 224, 448, 896, 1792, 3584, 7168, 14336, 28672, 57344, 114688, 229376, 458752, 917504, 1835008, 3670016, 7340032, 14680064, 29360128, 58720256, 117440512, 234881024, 469762048, 939524096, 1879048192, 3758096384, 7516192768, 15032385536 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (2).

FORMULA

a(1) = 1, a(2) = 3, a(n) = 7*2^(n-3) for n>=3.

a(n) = 2*a(n-1) for n>3. G.f.: -x*(x^2+x+1) / (2*x-1). - Colin Barker, Oct 12 2013

EXAMPLE

a(6) = 7*8 = 7*2^3. First few rows of A125175 are (1; 1,2; 1,3,3; 1,4,5,4;...). a(4) = 14 = (1 + 4 + 5 + 4).

MATHEMATICA

CoefficientList[Series[-(x^2 + x + 1)/(2 x - 1), {x, 0, 40}], x] (* Vincenzo Librandi, Oct 12 2013 *)

CROSSREFS

Cf. A125175.

Essentially identical to A005009.

Sequence in context: A140741 A088209 A089074 * A153234 A293334 A266625

Adjacent sequences:  A125173 A125174 A125175 * A125177 A125178 A125179

KEYWORD

nonn,easy

AUTHOR

Gary W. Adamson, Nov 22 2006

EXTENSIONS

More terms from N. J. A. Sloane, Dec 15 2007

STATUS

approved

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Last modified February 21 10:49 EST 2019. Contains 320372 sequences. (Running on oeis4.)