A213439 A000136(n)/2.

1, 3, 8, 25, 72, 231, 696, 2268, 7030, 23155, 73188, 242957, 778946, 2601345, 8430992, 28289598, 92470194, 311472985, 1025114180, 3463982109, 11465054942, 38846071490, 129180293184, 438697998100, 1464716085664, 4984101484479, 16698145444260, 56918978668875

Offset: 2

Author

N. J. A. Sloane, Jun 11 2012

Keywords

• nonn

References

• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

Crossrefs

Cf. A000136, A000560.