A329115 a(n) = floor(A026549(n)/5).

0, 0, 1, 2, 7, 14, 43, 86, 259, 518, 1555, 3110, 9331, 18662, 55987, 111974, 335923, 671846, 2015539, 4031078, 12093235, 24186470, 72559411, 145118822, 435356467, 870712934, 2612138803, 5224277606, 15672832819, 31345665638, 94036996915, 188073993830

Offset: 1

Author

Clark Kimberling, Nov 10 2019

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (0,7,0,-6).

Crossrefs

Cf. A026532, A329115.

Programs

Mathematica

s[1] = 1; s[n_] := If[IntegerQ[n/2], 2*s[n - 1], 3*s[n - 1]]
Table[s[n], {n, 1, 20}] (* A026532 *)
Table[Floor[s[n]/5], {n, 1, 50}] (* A329115 *)

Formula

a(n+1) = 2*a(n) if n is odd, a(n+1) = 3*a(n)+1 if n is even.

a(n) = f(2^f(n/2) * 3^f((n-1)/2) / 5), where f = floor.

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

a(n) = 7*a(n-2) - 6*a(n-4).