3,2

Jackson, D. M.; Reilly, J. W. Permutations with a prescribed number of $p$-runs. Ars Combinatoria 1 (1976), no. 1, 297-305.

J. Riordan, Permutations without 3-sequences, Bull. Amer. Math. Soc., 51 (1945), 745-748.

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

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Cf. A047921.

Sequence in context: A034726 A162274 A020078 this_sequence A065928 A114175 A080049

Adjacent sequences: A002626 A002627 A002628 this_sequence A002630 A002631 A002632

nonn,more

N. J. A. Sloane (njas(AT)research.att.com).