1,3

Self-convolution = the Robbins sequence, A005130: (1, 2, 7, 42, 429, 7436,...).

Example: A005130(4) = 42 = (1, 1, 3, 18) dot (18, 3, 1, 1) = (18 + 3 + 3 + 18).

The reversed procedure given (1, 2, 7, 42,...) for a(4) = 18 =

(1/2 * (42 - 2*a(3)) = 1/2 * 36 = 18.

Cf. A005130, A160708

Sequence in context: A141118 A033030 A002824 this_sequence A135077 A157538 A024488

Adjacent sequences: A160704 A160705 A160706 this_sequence A160708 A160709 A160710

nonn

Gary W. Adamson (qntmpkt(AT)yahoo.com), May 24 2009