A061482 a(1) = 1, a(2) = 2, a(n) = sum of products of previous terms taking n-2 at a time.

1, 2, 3, 11, 127, 16195, 262286407, 68794159432716139, 4732636372053966959311918076028751, 22397847030088134373054567592093233271179679420451463713205492138771

Offset

1,2

Comments

The next term (a(11)) has 135 digits. [From Harvey P. Dale, Feb 29 2012]

Links

Table of n, a(n) for n=1..10.

Example

a(3) = a(1) + a(2) = 3, a(4) = a(1)a(2) + a(2)a(3) + a(3)a(1) = 11, a(5) = 1*2*3 + 1*2*11 + 1*3*11 + 2*3*11 = 127.

Crossrefs

Cf. A061902 (lengths of terms).

Sequence in context: A050721 A058114 A042337 * A177854 A273598 A135161

Adjacent sequences: A061479 A061480 A061481 * A061483 A061484 A061485

Keyword

nonn,easy

Author

Amarnath Murthy, May 05 2001

Extensions

More terms from Asher Auel, May 05 2001. The 11th term has 135 digits.

Status

approved