A254232 Product of Perrin numbers A001608(2) * ... * A001608(n).

2, 6, 12, 60, 300, 2100, 21000, 252000, 4284000, 94248000, 2733192000, 106594488000, 5436318888000, 369669684384000, 33270271594560000, 3959162319752640000, 625547646520917120000, 130739458122871678080000, 36214829900035454828160000

Offset: 2

Author

Vaclav Kotesovec, Jan 27 2015

Keywords

• nonn

Links

• Chai Wah Wu, Table of n, a(n) for n = 2..127

Crossrefs

Cf. A001608, A003266, A060006, A126772, A135407, A254231.

Programs

Mathematica

Table[Product[SeriesCoefficient[(3-x^2)/(1-x^2-x^3),{x,0,k}],{k,2,n}], {n,2,20}]

Python

A254232_list, a, b, c, d = [2], 3, 0, 2, 2
for _ in range(200):
    a, b, c = b, c, a+b
    d *= c
    A254232_list.append(d) # Chai Wah Wu, Jan 28 2015

Formula

a(n) ~ c * r^(n*(n+1)/2), where r = A060006 = 1.324717957244746025960908854478... is the root of the equation r^3 = r + 1, c = 0.81845731383668335747954234022593868885066763327809025622515304041339344876... .