A164826 Sequences A087800 and A077416 interleaved.

2, 1, 12, 13, 142, 155, 1692, 1847, 20162, 22009, 240252, 262261, 2862862, 3125123, 34114092, 37239215, 406506242, 443745457, 4843960812, 5287706269, 57721023502, 63008729771, 687808321212, 750817050983, 8195978831042

Offset: 1

Author

Mark Dols, Aug 27 2009

Keywords

• nonn
• easy
• less

Links

• Index entries for linear recurrences with constant coefficients, signature (0,12,0,-1).

Crossrefs

Cf. A087800, A077416, A000032, A162671.

Programs

Mathematica

LinearRecurrence[{0,12,0,-1},{2,1,12,13},30] (* Harvey P. Dale, Oct 02 2017 *)

Formula

a(n) = a(n-1)+a(n-2) for n even, a(n) = 10*a(n-1)+a(n-2) for n odd; with a(1) = 2, a(2) = 1.

a(n) = 12*a(n-2)-a(n-4). G.f.: x*(x^3-12*x^2+x+2) / (x^4-12*x^2+1). [Colin Barker, Feb 18 2013]

Extensions

Better name by Paul Muljadi, Jan 13 2011