A320469 a(n) = 3*a(n-1) + 10*a(n-2), n >= 2; a(0)=1, a(1)=1.

1, 1, 13, 49, 277, 1321, 6733, 33409, 167557, 836761, 4185853, 20925169, 104634037, 523153801, 2615801773, 13078943329, 65394847717, 326973976441, 1634870406493, 8174350983889, 40871757016597, 204358780888681, 1021793912832013, 5108969547382849, 25544847770468677

Offset

0,3

Links

Table of n, a(n) for n=0..24.

Index entries for linear recurrences with constant coefficients, signature (3,10).

Formula

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

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

Prog

(PARI) {a(n) = (4*(-2)^n+3*5^n)/7}
(PARI) N=40; x='x+O('x^N); Vec((1-2*x)/((1-5*x)*(1+2*x)))

Crossrefs

Cf. A053428, A224473 (trimorphic number), A320468, A321133.

Sequence in context: A147452 A146782 A373578 * A074014 A147481 A245138

Adjacent sequences: A320466 A320467 A320468 * A320470 A320471 A320472

Keyword

nonn,easy

Author

Seiichi Manyama, Aug 27 2019

Status

approved