2,2

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

Choudum, S. A.; Parthasarathy, K. R. Semi-regular relations and digraphs. Nederl. Akad. Wetensch. Proc. Ser. A. {75}=Indag. Math. 34 (1972), 326-334.

Sequence in context: A065097 A122705 A024395 this_sequence A052351 A106111 A142786

Adjacent sequences: A003283 A003284 A003285 this_sequence A003287 A003288 A003289

nonn,nice,more

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