See Riordan  for details.
Table of n, a(n) for n=0..7.
John Riordan, Letter to N. J. A. Sloane, Sep 26 1980 with notes on the 1973 Handbook of Integer Sequences. Note that the sequences are identified by their N-numbers, not their A-numbers.
Sequence in context: A190943 A180912 A234280 * A302614 A220573 A303743
Adjacent sequences: A298010 A298011 A298012 * A298014 A298015 A298016
N. J. A. Sloane, Jan 11 2018