1,5
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Table of n, a(n) for n=1..11.
W. F. Lunnon, Counting multidimensional polyominoes. Computer Journal 18 (1975), no. 4, pp. 366-367.
A column of A195738.
Sequence in context: A220933 A222321 A222138 * A144340 A247020 A059580
Adjacent sequences: A006757 A006758 A006759 * A006761 A006762 A006763
nonn,more
N. J. A. Sloane.
approved