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A168374 a(n) = 7 * floor(n/2). 4
0, 7, 7, 14, 14, 21, 21, 28, 28, 35, 35, 42, 42, 49, 49, 56, 56, 63, 63, 70, 70, 77, 77, 84, 84, 91, 91, 98, 98, 105, 105, 112, 112, 119, 119, 126, 126, 133, 133, 140, 140, 147, 147, 154, 154, 161, 161, 168, 168, 175, 175, 182, 182, 189, 189, 196, 196, 203, 203, 210 (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 (1,1,-1).

FORMULA

a(n) = 7*n - a(n-1) - 7, with n>1, a(1)=0.

G.f.: 7*x^2/((1+x)*(1-x)^2). - Bruno Berselli, Sep 17 2013

a(n) = 7*A004526(n). - Bruno Berselli, Sep 17 2013

E.g.f.: (7/2)*(x*cosh(x) + (x - 1)*sinh(x)). - G. C. Greubel, Jul 19 2016

MATHEMATICA

CoefficientList[Series[7 x/((1 + x) (1 - x)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 17 2013 *)

Table[7 Floor[n/2], {n, 60}] (* Bruno Berselli, Sep 18 2013 *)

PROG

(MAGMA) [n eq 1 select 0 else 7*n-Self(n-1)-7: n in [1..70]]; // Vincenzo Librandi, Sep 17 2013

CROSSREFS

Cf. A004526, A008589.

Sequence in context: A173314 A040043 A003872 * A112438 A309459 A022090

Adjacent sequences:  A168371 A168372 A168373 * A168375 A168376 A168377

KEYWORD

nonn,easy,less

AUTHOR

Vincenzo Librandi, Nov 24 2009

EXTENSIONS

New definition by Bruno Berselli, Sep 18 2013

STATUS

approved

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Last modified August 20 08:27 EDT 2019. Contains 326143 sequences. (Running on oeis4.)