Riordan numbers: Difference between revisions

=={{header|PL/I}}==

<lang pli>showRiordan: procedure options( main ); /* find some Riordan numbers */

%replace maxRiordan by 32;

/* sets a to the first n riordan numbers a must have bounds 1 : n */

/* so the first number has index 1, not 0 */

riordan: procedure( n, a );

declare n binary( 15 )fixed;

declare a ( maxRiordan )decimal( 14 );

declare ( r2, r1, ri, i ) decimal( 14 );

if n >= 1 then do;

r2 = 1;

a( 1 ) = r2;

if n >= 2 then do;

r1 = 0;

a( 2 ) = r1;

do i = 2 to n;

ri = ( ( i - 1 )

* ( ( 2 * r1 )

+ ( 3 * r2 )

)

)

/ ( i + 1 );

a( i + 1 ) = ri;

r2 = r1;

r1 = ri;

end;

end;

end;

end riordan ;

declare r ( maxRiordan )decimal( 14 ), i binary( 15 )fixed;

call riordan( maxRiordan, r );

do i = 1 to maxRiordan;

put list( ' ', r( i ) );

if mod( i, 4 ) = 0 then put skip;

end;

end showRiordan;</lang>

{{out}}

<pre>

1 0 1 1

3 6 15 36

91 232 603 1585

4213 11298 30537 83097

227475 625992 1730787 4805595

13393689 37458330 105089229 295673994

834086421 2358641376 6684761125 18985057351

54022715451 154000562758 439742222071 1257643249140

</pre>