A166023 a(n) = 6*a(n-2) for n > 2; a(1) = 1, a(2) = 5.

1, 5, 6, 30, 36, 180, 216, 1080, 1296, 6480, 7776, 38880, 46656, 233280, 279936, 1399680, 1679616, 8398080, 10077696, 50388480, 60466176, 302330880, 362797056, 1813985280, 2176782336, 10883911680, 13060694016, 65303470080, 78364164096

Offset: 1

Author

Klaus Brockhaus, Oct 04 2009

Keywords

• nonn
• easy

Comments

Interleaving of A000400 and 5*A000400.

Fifth binomial transform is A154236.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..300
• Index entries for linear recurrences with constant coefficients, signature (0, 6).

Crossrefs

Cf. A000400 (powers of 6), A154236.

Programs

Magma

[ n le 2 select 4*n-3 else 6*Self(n-2): n in [1..29] ];

Mathematica

LinearRecurrence[{0, 6}, {1, 5}, {1, 50}] (* G. C. Greubel, Apr 21 2016 *)

Formula

a(n) = 6^(1/4*(2*n+3+(-1)^n))*(11-(-1)^n)/72.

G.f.: x*(1+5*x)/(1-6*x^2).