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A168094 a(n) = number of natural numbers m such that n - 4 <= m <= n + 4. 0
4, 5, 6, 7, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9 (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..89.

FORMULA

a(n) = 4 + n for 0 <= n <= 4, a(n) = 9 for n >= 4.

G.f.: (4 - 3*x - x^6)/(1 - x)^2. - G. C. Greubel, Jul 12 2016

MATHEMATICA

CoefficientList[Series[(4 - 3*x - x^6)/(1 - x)^2, {x, 0, 25}], x] (* G. C. Greubel, Jul 12 2016 *)

CROSSREFS

Cf. A000027.

Sequence in context: A178053 A090925 A143836 * A089166 A178052 A030543

Adjacent sequences:  A168091 A168092 A168093 * A168095 A168096 A168097

KEYWORD

nonn,less

AUTHOR

Jaroslav Krizek, Nov 18 2009

STATUS

approved

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Last modified July 14 19:48 EDT 2020. Contains 335729 sequences. (Running on oeis4.)