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

Author

Reinhard Zumkeller, Apr 04 2012

Keywords

• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0,0,12).

Crossrefs

Cf. A001222, A052901, A026549, A026532.

Programs

Haskell

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

Mathematica

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

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