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

1,1

Links

Table of n, a(n) for n=1..25.

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

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]

Mathematica

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

Crossrefs

Cf. A087800, A077416, A000032, A162671.

Sequence in context: A278330 A048854 A151508 * A055392 A045873 A371637

Adjacent sequences: A164823 A164824 A164825 * A164827 A164828 A164829

Keyword

nonn,easy,less

Author

Mark Dols, Aug 27 2009

Extensions

Better name by Paul Muljadi, Jan 13 2011

Status

approved