Table of n, a(n) for n=0..20.
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.
Riordan gives a recurrence.
Sequence in context: A125793 A121145 A144882 * A006681 A074876 A238722
Adjacent sequences: A298009 A298010 A298011 * A298013 A298014 A298015
N. J. A. Sloane, Jan 10 2018