A136102 - OEIS

A136102

Triangle read by rows, in which rows give signatures for Ferrers boards fitting inside staircases coded 1, 2, 12, 360, 75600, ... (see A006939).

%I #2 Mar 31 2012 13:23:39

%S 1,1,2,1,2,4,6,12,1,2,4,6,8,12,24,30,36,60,72,120,180,360,1,2,4,6,8,

%T 12,16,24,30,36,48,60,72,120,144,180,210,216,240,360,420,32,720,840,

%U 900,1080,1260,1680,1800,2160,2520,3600,5040,5400,6300,7560,10800,12600

%N Triangle read by rows, in which rows give signatures for Ferrers boards fitting inside staircases coded 1, 2, 12, 360, 75600, ... (see A006939).

%C The number of signatures on each row is 1 2 5 14 42 132 ... cf. A000108.

%D G. E. Andrews and K. Eriksson, Integer Partitions, Cambridge Univ. Press, 2004. page 22 Exer. 33.

%e The irregular array begins

%e 1

%e 1 2

%e 1 2 4 6 12

%e 1 2 4 6 8 12 24 30 36 60 72 120 180 360

%Y Cf. A000041 A000108 A006939 A025487.

%K easy,nonn,tabf

%O 1,3

%A _Alford Arnold_, Jan 12 2008