A173773 a(3*n) = 8*n+2, a(3*n+1) = 2*n+1, a(3*n+2) = 8*n+6.

2, 1, 6, 10, 3, 14, 18, 5, 22, 26, 7, 30, 34, 9, 38, 42, 11, 46, 50, 13, 54, 58, 15, 62, 66, 17, 70, 74, 19, 78, 82, 21, 86, 90, 23, 94, 98, 25, 102, 106, 27, 110, 114, 29, 118, 122, 31, 126, 130, 33, 134, 138, 35, 142, 146, 37, 150, 154, 39, 158, 162, 41, 166

Offset: 0

Author

Paul Curtz, Nov 26 2010

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (0,0,2,0,0,-1).

Crossrefs

Cf. A005408, A017089, A017137.

Programs

Mathematica

Table[Sequence @@ {8*n+2, 2*n+1,  8*n+6}, {n, 0, 20}] (* Amiram Eldar, Oct 08 2023 *)

Formula

G.f.: (1+x)*(2-x+7*x^2-x^3+2*x^4)/(1-x^3)^2.

Sum_{n>=0} (-1)^(n+1)/a(n) = (2-sqrt(2))*Pi/8. - Amiram Eldar, Oct 08 2023