A180236 a(n) = a(n-2)+a(n-4); a(1)=a(4)=101, a(2)=a(3)=10.

101, 10, 10, 101, 111, 111, 121, 212, 232, 323, 353, 535, 585, 858, 938, 1393, 1523, 2251, 2461, 3644, 3984, 5895, 6445, 9539, 10429, 15434, 16874, 24973, 27303, 40407, 44177, 65380, 71480, 105787, 115657, 171167, 187137, 276954, 302794, 448121, 489931

Offset: 1

Author

Mark Dols, Aug 18 2010

Keywords

• nonn
• easy

Comments

Generalization of A115339.

Links

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

Crossrefs

Cf. A115339, A000045, A000032.

Programs

Mathematica

LinearRecurrence[{0,1,0,1},{101,10,10,101},50] (* Paolo Xausa, Jan 04 2024 *)

PARI

Vec(-x*(91*x^3-91*x^2+10*x+101)/(x^4+x^2-1) + O(x^100)) \\ Colin Barker, Oct 03 2015

PARI

a(n) = if(n==1||n==4, 101, if(n==2||n==3, 10, a(n-2)+a(n-4))); \\ Altug Alkan, Oct 03 2015

Formula

G.f.: -x*(91*x^3-91*x^2+10*x+101) / (x^4+x^2-1). Colin Barker, Oct 03 2015