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A230053 Recurrence a(n+2) = (n+2)*a(n+1)*a(n), with a(0) = a(1) = 1. 1
1, 1, 2, 6, 48, 1440, 414720, 4180377600, 13869489586176000, 521817332305350780518400000, 72373400562952038729626622187536384000000000, 415422642927888257689749131592471020852730170822782196121600000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Numbers of decimal digits in a(n) for 0 <= n <= 20: 1, 1, 1, 1, 2, 4, 6, 10, 17, 27, 44, 72, 117, 190, 307, 498, 806, 1305, 2112, 3417, 5530. - Robert Israel, Oct 09 2017

LINKS

Robert Israel, Table of n, a(n) for n = 0..16

FORMULA

a(n) = Product_{k=0..n-1} (n-k+1)^Fibonacci(k).

MAPLE

f:= proc(n) option remember; n*procname(n-1)*procname(n-2) end proc:

f(0):= 1: f(1):= 1:

map(f, [$0..12]); # Robert Israel, Oct 08 2017

MATHEMATICA

RecurrenceTable[{a[n + 2] == (n + 2) a[n + 1] a[n], a[0] == a[1] == 1}, a, {n, 0, 12}] (* or *)

Table[Product[(n - k + 1)^Fibonacci[k], {k, 0, n - 1}], {n, 0, 12}]

CROSSREFS

Cf. A000045.

Sequence in context: A063744 A141609 A096313 * A245283 A126023 A088679

Adjacent sequences:  A230050 A230051 A230052 * A230054 A230055 A230056

KEYWORD

nonn

AUTHOR

Emanuele Munarini, Oct 08 2017

STATUS

approved

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Last modified February 27 01:52 EST 2020. Contains 332299 sequences. (Running on oeis4.)