1,1

a(n) = 2*a(n-2)+7 for n > 2; a(1) = 5, a(2) = 7.

a(n) = (19-5*(-1)^n)*2^(1/4*(2*n-1+(-1)^n))/2-7.

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

(MAGMA) T:=[ n le 2 select 8-3*n else 2*Self(n-2): n in [1..38] ]; [ n eq 1 select T[1] else Self(n-1)+T[n]: n in [1..#T]];

Cf. A162396, A164053 (partial sums of A162255).

Sequence in context: A128491 A146949 A048700 this_sequence A043879 A044966 A145354

Adjacent sequences: A164117 A164118 A164119 this_sequence A164121 A164122 A164123

nonn

Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Aug 10 2009