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A060242 a(n) = (2^n - 1)*(4^n - 1). 1
0, 3, 45, 441, 3825, 31713, 257985, 2080641, 16711425, 133955073, 1072692225, 8585738241, 68702695425, 549688696833, 4397778059265, 35183298314241, 281470681677825, 2251782633684993, 18014329789743105, 144114913197424641, 1152920405094170625 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
G.f.: 3*x*(1-8*x^2)/((1-x)*(1-2*x)*(1-4*x)*(1-8*x)). - Alois P. Heinz, Feb 19 2021
MAPLE
f:= gfun:-rectoproc({a(n) - 15*a(n-1) + 70*a(n-2) - 120*a(n-3) + 64*a(n-4) = 0, a(0) = 0, a(1)=3, a(2)=45, a(3)=441}, a(n), remember): map(f, [$0..20]); # Georg Fischer, Feb 19 2021
MATHEMATICA
Table[(2^n-1)(4^n-1), {n, 0, 20}] (* Harvey P. Dale, May 13 2019 *)
PROG
(PARI) a(n) = (2^n - 1)*(4^n - 1)); \\ Harry J. Smith, Jul 04 2009
CROSSREFS
Sequence in context: A061532 A309453 A360716 * A271236 A270064 A141445
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 22 2001
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)