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A002266 Integers repeated 5 times. 41
0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 16, 16, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,11

COMMENTS

For n > 3, number of consecutive "11's" after the (n+3) "1's" in the continued fraction for sqrt(L(n+2)/L(n)) where L(n) is the n-th Lucas number A000002 (see example). E.g., the continued fraction for sqrt(L(11)/L(9)) is [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 11, 11, 58, 2, 4, 1, ...] with 12 consecutive ones followed by floor(11/5)=2 elevens. - Benoit Cloitre, Jan 08 2006

Complement of A010874, since A010874(n) + 5*a(n) = n. - Hieronymus Fischer, Jun 01 2007

LINKS

Table of n, a(n) for n=0..82.

Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1).

FORMULA

a(n) = floor(n/5), n >= 0.

G.f.: x^5/((1-x)(1-x^5)).

a(n)= -1 + Sum_{k=0..n} ((8*(sin(2*Pi*k/5))^2-5)^2-5)/20, with n>=0. a(n)= -1 + Sum_{k=0..n} (1/50)*(-9*(k mod 5) + ((n+1) mod 5) + ((n+2) mod 5) + ((n+3) mod 5) + 11*((n+4) mod 5)), with n >= 0. - Paolo P. Lava, May 15 2007

a(n) = (n - A010874(n))/5. - Hieronymus Fischer, May 29 2007

Also, floor((n^5-1)/5*n^4) will produce this sequence. Moreover, floor((n^5-n^4)/(5*n^4-4*n^3)) (n >= 1) will produce this sequence as well. - Mohammad K. Azarian, Nov 08 2007

This sequence is also the sequence floor(n*e^(-(1+sqrt(5))/2))(n >= 1). - Mohammad K. Azarian, May 13 2008

For n >= 5, a(n) = floor(log_5(5^a(n-1) + 5^a(n-2) + 5^a(n-3) + 5^a(n-4) + 5^a(n-5))). - Vladimir Shevelev, Jun 22 2010

MAPLE

A002266:=n->floor(n/5); seq(A002266(n), n=0..100); # Wesley Ivan Hurt, Dec 10 2013

MATHEMATICA

Table[Floor[n/5], {n, 0, 20}] (* Wesley Ivan Hurt, Dec 10 2013 *)

PROG

(Sage) [floor(n/5) - 1 for n in xrange(5, 88)] # Zerinvary Lajos, Dec 01 2009

(Haskell)

a002266 = (`div` 5)

a002266_list = [0, 0, 0, 0, 0] ++ map (+ 1) a002266_list

-- Reinhard Zumkeller, Nov 27 2012

(PARI) a(n)=n\5 \\ Charles R Greathouse IV, Dec 10 2013

CROSSREFS

a(n) = A010766(n, 5).

Cf. A008648, A004526, A002264, A002265, A010761, A010762, A110532, A110533, A004526, A010872, A010873, A010874.

Partial sums: A130520.

Sequence in context: A235402 A092278 A105512 * A075249 A008648 A154099

Adjacent sequences:  A002263 A002264 A002265 * A002267 A002268 A002269

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified February 20 10:26 EST 2018. Contains 299385 sequences. (Running on oeis4.)