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
Keywords
Links
- 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.