1,2

Interleaving of A000244 and 4*A000244.

Apparently a(n) = A074324(n); A074324 has offset 0.

First differences are in A162852.

Second binomial transform is A054491. Fourth binomial transform is A153594.

a(n) = (7+(-1)^n)*3^(1/4*(2*n-5+(-1)^n))/2.

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

(MAGMA) [ n le 2 select 3*n-2 else 3*Self(n-2): n in [1..35] ];

Equals A162766 preceded by 1.

Cf. A000244 (powers of 3), A074324, A162852, A054491, A153594.

Sequence in context: A055523 A074324 A162766 this_sequence A122804 A122544 A054908

Adjacent sequences: A166549 A166550 A166551 this_sequence A166553 A166554 A166555

nonn

Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 16 2009