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A168437 a(n) = 3 + 10*floor(n/2). 2
3, 13, 13, 23, 23, 33, 33, 43, 43, 53, 53, 63, 63, 73, 73, 83, 83, 93, 93, 103, 103, 113, 113, 123, 123, 133, 133, 143, 143, 153, 153, 163, 163, 173, 173, 183, 183, 193, 193, 203, 203, 213, 213, 223, 223, 233, 233, 243, 243, 253, 253, 263, 263, 273, 273, 283 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = 10*n - a(n-1) - 4, with n>1, a(1) = 3.
a(n) = 10*floor(n/2) + 3 = A168641(n) + 3. - Rick L. Shepherd, Jun 17 2010
G.f.: x*(3 + 10*x - 3*x^2)/((1+x)*(x-1)^2). - Vincenzo Librandi, Sep 19 2013
a(n) = a(n-1) +a(n-2) -a(n-3). - Vincenzo Librandi, Sep 19 2013
a(n) = (1 + 5*(-1)^n + 10*n)/2. - Bruno Berselli, Sep 19 2013
E.g.f.: (1/2)*(5 - 6*exp(x) + (10*x + 1)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 22 2016
MATHEMATICA
Table[3 + 10 Floor[n/2], {n, 70}] (* or *) CoefficientList[Series[(3 + 10 x - 3 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 2013 *)
LinearRecurrence[{1, 1, -1}, {3, 13, 13}, 70] (* Harvey P. Dale, May 26 2021 *)
PROG
(PARI) a(n)=n\2*10+3 \\ Charles R Greathouse IV, Jan 11 2012
(Magma) [3+10*Floor(n/2): n in [1..70]]; // Vincenzo Librandi, Sep 19 2013
CROSSREFS
Bisections of A168437 are A017305 and (A017305 MINUS {3}). - Rick L. Shepherd, Jun 17 2010
Sequence in context: A272825 A054767 A137947 * A076747 A198452 A286190
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 25 2009
EXTENSIONS
Edited by Rick L. Shepherd, Jun 17 2010
Definition rewritten, using Shepherd's formula, by Vincenzo Librandi, Sep 19 2013
STATUS
approved

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Last modified March 29 06:34 EDT 2024. Contains 371265 sequences. (Running on oeis4.)