A276278 Complement of A026474.

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

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: A242437 A370301 A188916 * A277727 A080943 A363690

Adjacent sequences: A276275 A276276 A276277 * A276279 A276280 A276281

Keyword

nonn,easy

Author

Bob Selcoe, Aug 26 2016

Status

approved