A127641 - OEIS

%I #7 Aug 18 2015 00:10:09

%S 2,3,3,5,0,5,7,7,0,7,11,0,0,0,11,13,13,13,0,0,13,17,0,0,0,0,0,17,19,

%T 19,0,19,0,0,0,19,23,0,23,0,0,0,0,0,23,29,29,0,0,29,0,0,0,0,29,31,0,0,

%U 0,0,0,0,0,0,0,31,37,37,37,37,0,37,0,0,0,0,0,37,41,0,0,0,0,0,0,0,0,0,0,0,41

%N A127640 * A051731 as infinite lower triangular matrices.

%C A prime transform of A051731.

%e First few rows of the triangle are:

%e 2;

%e 3, 3;

%e 5, 0, 5;

%e 7, 7, 0, 7;

%e 11, 0, 0, 0, 11;

%e 13, 13, 13, 0, 0, 13;

%e ...

%p A127640 := proc(n,m) if m < n then 0; else ithprime(n) ; fi ; end: A051731 := proc(n,k) if n mod k = 0 then 1 ; else 0 ; fi ; end: A127641 := proc(n,m) add( A127640(n,k)*A051731(k,m),k=1..n) ; end: for n from 1 to 15 do for m from 1 to n do printf("%d,",A127641(n,m)) ; od ; od ; # _R. J. Mathar_, May 19 2007

%Y Cf. A127640, A051731, A127638, A127639.

%K nonn,tabl,easy

%O 1,1

%A _Gary W. Adamson_, Jan 21 2007

%E More terms from _R. J. Mathar_, May 19 2007