2,2

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

J. Riordan, The number of impedances of an n-terminal network, Bell Syst. Tech. J., 18 (1939), 300-314.

Cf. A003128, A003129.

Sequence in context: A158546 A110216 A036276 this_sequence A015000 A112719 A091019

Adjacent sequences: A003127 A003128 A003129 this_sequence A003131 A003132 A003133

nonn

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