A282848 a(n) = 2*n + 1 + n mod 4.

4, 7, 10, 9, 12, 15, 18, 17, 20, 23, 26, 25, 28, 31, 34, 33, 36, 39, 42, 41, 44, 47, 50, 49, 52, 55, 58, 57, 60, 63, 66, 65, 68, 71, 74, 73, 76, 79, 82, 81, 84, 87, 90, 89, 92, 95, 98, 97, 100, 103, 106, 105, 108, 111, 114, 113, 116, 119, 122, 121, 124, 127

Offset: 1

Author

Zak Seidov, Feb 23 2017

Keywords

• nonn
• easy

Links

• Colin Barker, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).

Crossrefs

Cf. A143097, A083220.

Programs

Mathematica

Table[2*k + 1 + Mod[k, 4], {k, 100}]
CoefficientList[ Series[(4 + 3 x + 3 x^2 - x^3 - x^4)/((x -1)^2 (1 + x + x^2 + x^3)), {x, 0, 60}], x] (* or *)
LinearRecurrence[{1, 0, 0, 1, -1}, {4, 7, 10, 9, 12}, 70] (* Robert G. Wilson v, Feb 23 2017 *)

PARI

Vec(x*(4 + 3*x + 3*x^2 - x^3 - x^4) / ((1 - x)^2*(1 + x)*(1 + x^2)) + O(x^100)) \\ Colin Barker, Feb 23 2017

Formula

For n > 4 a(n) = a(n - 4) + 8.

G.f.: x*(4 + 3*x + 3*x^2 - x^3 - x^4) / ((1 - x)^2*(1 + x)*(1 + x^2)). - Colin Barker, Feb 23 2017