A298012 a(0)=a(1)=0; thereafter a(n) = A162973(n)/(n-1).

0, 0, 1, 1, 4, 16, 85, 533, 3888, 32268, 300193, 3093377, 34970468, 430293488, 5724411845, 81871668773, 1252691817856, 20417647146396, 353169795861921, 6461418976274657, 124664729763630436

Offset

0,5

Links

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.

Formula

Riordan gives a recurrence.

Crossrefs

Sequence in context: A125793 A121145 A144882 * A006681 A074876 A238722

Adjacent sequences: A298009 A298010 A298011 * A298013 A298014 A298015

Keyword

nonn

Author

N. J. A. Sloane, Jan 10 2018

Status

approved