A208131 Partial products of A052901.

1, 3, 6, 12, 36, 72, 144, 432, 864, 1728, 5184, 10368, 20736, 62208, 124416, 248832, 746496, 1492992, 2985984, 8957952, 17915904, 35831808, 107495424, 214990848, 429981696, 1289945088, 2579890176, 5159780352, 15479341056, 30958682112, 61917364224, 185752092672

Offset

0,2

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0,0,12).

Formula

a(n+1) = a(n) * A052901(n).

A001222(a(n)) = n.

a(n) = 12^floor(n/3)*(r+1)*(r+2)/2 with r = n mod 3. G.f.: -(6*x^2+3*x+1) / (12*x^3-1). - Alois P. Heinz, Apr 05 2012

Sum_{n>=0} 1/a(n) = 18/11. - Amiram Eldar, Feb 13 2023

Mathematica

FoldList[Times, 1, PadRight[{}, 30, {3, 2, 2}]] (* Harvey P. Dale, Mar 19 2013 *)

Prog

(Haskell)
a208131 n = a208131_list !! n
a208131_list = scanl (*) 1 $ a052901_list
-- Reinhard Zumkeller, Mar 29 2012

Crossrefs

Cf. A001222, A052901, A026549, A026532.

Sequence in context: A102972 A075209 A075207 * A136121 A023369 A358058

Adjacent sequences: A208128 A208129 A208130 * A208132 A208133 A208134

Keyword

nonn

Author

Reinhard Zumkeller, Apr 04 2012

Status

approved