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A171892 0, 1 and all numbers >= 9. 1
0, 1, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Used to illustrate Besicovitch's density theorem.

REFERENCES

H. Halberstam and K. F. Roth, Sequences, Oxford, 1966; see p. 6.

LINKS

Table of n, a(n) for n=1..71.

Index entries for linear recurrences with constant coefficients, signature (2,-1).

FORMULA

G.f.: x^2*(1+7*x-7*x^2)/(1-x)^2.  - Bruno Berselli, Sep 02 2011

MATHEMATICA

Complement[Range[0, 100], Range[2, 8]] (* Harvey P. Dale, Oct 10 2014 *)

PROG

(PARI) a(n)=if(n>2, n+6, n-1) \\ Charles R Greathouse IV, Sep 02 2011

CROSSREFS

Sequence in context: A095777 A168099 A004498 * A020723 A317591 A107043

Adjacent sequences:  A171889 A171890 A171891 * A171893 A171894 A171895

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Oct 19 2010

STATUS

approved

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Last modified December 12 22:06 EST 2019. Contains 329963 sequences. (Running on oeis4.)