A063401 a(n) = a(n-1)*a(n-2)*a(n-3) with a(0)=1, a(1)=2, a(2)=2.

1, 2, 2, 4, 16, 128, 8192, 16777216, 17592186044416, 2417851639229258349412352, 713623846352979940529142984724747568191373312, 30354201441027016733116592294117482916287606860189680019559568902170379456331382784

Offset

0,2

Links

Harry J. Smith, Table of n, a(n) for n=0,...,15

Formula

a(n) = 2^A000073(n+1).

Example

a(6) = 128*16*4 = 8192.

Mathematica

a0=1; a1=1; a2=2; lst={a0, a1, a2}; Do[AppendTo[lst, a=a0*a1*a2]; a0=a1; a1=a2; a2=a, {n, 12}]; lst (* Vladimir Joseph Stephan Orlovsky, Nov 18 2009 *)
RecurrenceTable[{a[0]==1, a[1]==a[2]==2, a[n]==a[n-1]a[n-2]a[n-3]}, a, {n, 12}] (* Harvey P. Dale, Sep 05 2021 *)

Prog

(PARI) { for (n = 0, 15, if (n>2, a=a1*a2*a3; a3=a2; a2=a1; a1=a, if (n==0, a=a3=1; a1=a2=2, a=2)); write("b063401.txt", n, " ", a) ) } \\ Harry J. Smith, Aug 20 2009

Crossrefs

Cf. A000301, A000308.

Sequence in context: A032318 A090753 A091788 * A168088 A168089 A165420

Adjacent sequences: A063398 A063399 A063400 * A063402 A063403 A063404

Keyword

nonn

Author

Henry Bottomley, Jul 16 2001

Extensions

Definition corrected to a(1)=2 by Harry J. Smith, Aug 20 2009

Status

approved