login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A104570 Triangle read by rows: T(i,j) is the (i,j)-entry (1 <= j <= i) of the product R*Q of the infinite lower triangular matrices R = [1; 1,1; 1,1,1; 1,1,1,1;...] and Q = [1; 1,3; 1,3,1; 1 3,1,3; ...]. 2

%I

%S 1,2,3,3,6,1,4,9,2,3,5,12,3,6,1,6,15,4,9,2,3,7,18,5,12,3,6,1,8,21,6,

%T 15,4,9,2,3,9,24,7,18,5,12,3,6,1,10,27,8,21,6,15,4,9,2,3,11,30,9,24,7,

%U 18,5,12,3,6,1,12,33,10,27,8,21,6,15,4,9,2,3,13,36,11,30,9,24,7,18,5,12,3,6

%N Triangle read by rows: T(i,j) is the (i,j)-entry (1 <= j <= i) of the product R*Q of the infinite lower triangular matrices R = [1; 1,1; 1,1,1; 1,1,1,1;...] and Q = [1; 1,3; 1,3,1; 1 3,1,3; ...].

%F Even columns (offset) = 1, 2, 3, ...; while odd columns = 3, 6, 9, ...

%F T(i,j) = i-j+1 if j <= i and j is odd; 3(i-j+1) if j <= i and j is even. - _Emeric Deutsch_, Mar 23 2005

%e The first few rows of the triangle are:

%e 1;

%e 2, 3;

%e 3, 6, 1;

%e 4, 9, 2, 3;

%e ...

%p T:=proc(i,j) if j>i then 0 elif j mod 2 = 1 then i-j+1 else 3*(i-j+1) fi end:for i from 1 to 14 do seq(T(i,j),j=1..i) od; # yields sequence in triangular form # _Emeric Deutsch_, Mar 23 2005

%Y Cf. A035608, A074377, A104569.

%Y Row sums yield A035608. The product Q*R yields A104569.

%K nonn,tabl

%O 1,2

%A _Gary W. Adamson_, Mar 16 2005

%E More terms from _Emeric Deutsch_, Mar 23 2005

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 5 04:30 EDT 2020. Contains 335459 sequences. (Running on oeis4.)