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A276278 Complement of A026474. 0
3, 5, 6, 7, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 79 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers of the form prime(k)^a(n) do not appear in A026477.

Terms are all the positive integers except 1, 2, 4 and numbers of the form 7k+1.

LINKS

Table of n, a(n) for n=1..65.

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

FORMULA

For n>=2, a(n) = n + ceiling((n+2)/6) + 2.

For n>=8, a(n) = a(n-6) + 7.

G.f.: (3+2*x+x^2+x^3+2*x^4+x^5-2*x^6-x^7)/(1-x-x^6+x^7). - Robert Israel, Sep 09 2016

MAPLE

3, seq(n + ceil((n+2)/6)+2, n=2..100); # Robert Israel, Sep 09 2016

MATHEMATICA

Join[{3}, LinearRecurrence[{1, 0, 0, 0, 0, 1, -1}, {5, 6, 7, 9, 10, 11, 12}, 100]] (* Vincenzo Librandi, Aug 27 2016 *)

PROG

(PARI) a(n)=if(n>1, n+(n+7)\6, 2) \\ Charles R Greathouse IV, Aug 27 2016

(PARI) Vec((3+2*x+x^2+x^3+2*x^4+x^5-2*x^6-x^7)/(1-x-x^6+x^7) + O(x^99)) \\ Altug Alkan, Sep 09 2016

(MAGMA) [n+Ceiling((n+2)/6)+2: n in [0..100]]; // Vincenzo Librandi, Aug 27 2016

CROSSREFS

Cf. A026474, A026477.

Sequence in context: A184987 A242437 A188916 * A277727 A080943 A052294

Adjacent sequences:  A276275 A276276 A276277 * A276279 A276280 A276281

KEYWORD

nonn,easy

AUTHOR

Bob Selcoe, Aug 26 2016

STATUS

approved

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Last modified October 25 22:20 EDT 2021. Contains 348256 sequences. (Running on oeis4.)