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A168096 a(n) = number of natural numbers m such that n - 6 <= m <= n + 6. 0
6, 7, 8, 9, 10, 11, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Generalization: If a(n,k) = number of natural numbers m such that n - k <= m <= n + k (k >= 1) then a(n,k) = a(n-1,k) + 1 = n + k for 0 <= n <= k, a(n,k) = a(n-1,k) = 2k + 1 for n >= k + 1 (see, e.g., A158799).

LINKS

Table of n, a(n) for n=0..54.

FORMULA

a(n) = 6 + n for 0 <= n <= 6, a(n) = 13 for n >= 7.

G.f.: (6 - 5*x - x^8)/(1-x)^2. - G. C. Greubel, Jul 12 2016

MATHEMATICA

CoefficientList[Series[(6 - 5*x - x^8)/(1 - x)^2, {x, 0, 25}], x] (* G. C. Greubel, Jul 12 2016 *)

CROSSREFS

Cf. A000027.

Sequence in context: A168679 A102304 A114459 * A030546 A028253 A020715

Adjacent sequences:  A168093 A168094 A168095 * A168097 A168098 A168099

KEYWORD

nonn,less

AUTHOR

Jaroslav Krizek, Nov 18 2009

STATUS

approved

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Last modified July 4 14:29 EDT 2020. Contains 335448 sequences. (Running on oeis4.)