1,1

1 is not in the sequence because a 1 X 1 matrix does not contain a 2 X 2 submatrix. - Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 02 2008

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

Problem E2429, Amer. Math. Monthly, 81 (1974), 1112-1113.

Index entries for sequences related to binary matrices

Since k(2) = 2 then a(1) = 2

Since k(3) = k(4) = k(5) = k(6) = 3 then a(2) = 6

Since k(7) = k(8) = ... = k(12) = 4 then a(3) = 12

Since k(13) = k(14) = ... = k(20) = 5 then a(4) = 20

Since k(21) = k(22) = ... = k(30) = 6 then a(5) = 30

Since k(31) = k(32) = ... = k(43) = 7 then a(6) = 43

Sequence in context: A160929 A103505 A002378 this_sequence A003274 A121315 A078878

Adjacent sequences: A005988 A005989 A005990 this_sequence A005992 A005993 A005994

nonn,more

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

Edited by Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 02 2008