3,5
M. Gardner, The Last Recreations, Springer, 1997, p. 282.
Cf. A051567-A051570, A051754-A051759, A019654.
Sequence in context: A002700 A005724 A093376 * A019654 A156356 A143640
Adjacent sequences: A051568 A051569 A051570 * A051572 A051573 A051574
nonn,more
N. J. A. Sloane (njas(AT)research.att.com).
Probably an incorrect version of A019654.