cp's OEIS Frontend

A154724 Triangle read by rows in which row n lists 2n-1 terms: n, in the center of the row and the pairs of prime numbers that are equidistant to n, with 0's inserted, as shown below in the example.

%I A154724 #15 Apr 26 2025 15:26:10
%S A154724 1,0,2,0,0,0,3,0,0,0,0,3,4,5,0,0,0,0,3,0,5,0,7,0,0,0,0,0,0,5,6,7,0,0,
%T A154724 0,0,0,0,3,0,0,0,7,0,0,0,11,0,0,0,0,3,0,5,0,0,8,0,0,11,0,13,0,0,0,0,0,
%U A154724 0,5,0,7,0,9,0,11,0,13,0,0,0,0
%N A154724 Triangle read by rows in which row n lists 2n-1 terms: n, in the center of the row and the pairs of prime numbers that are equidistant to n, with 0's inserted, as shown below in the example.
%H A154724 Nathaniel Johnston, <a href="/A154724/b154724.txt">Table of n, a(n) for n = 1..10000</a>
%e A154724 Triangle begins:
%e A154724                              1
%e A154724                           0, 2, 0
%e A154724                        0, 0, 3, 0, 0
%e A154724                     0, 0, 3, 4, 5, 0, 0
%e A154724                  0, 0, 3, 0, 5, 0, 7, 0, 0
%e A154724               0, 0, 0, 0, 5, 6, 7, 0, 0, 0, 0
%e A154724            0, 0, 3, 0, 0, 0, 7, 0, 0, 0,11, 0, 0
%e A154724         0, 0, 3, 0, 5, 0, 0, 8, 0, 0,11, 0,13, 0, 0
%e A154724      0, 0, 0, 0, 5, 0, 7, 0, 9, 0,11, 0,13, 0, 0, 0, 0
%e A154724   0, 0, 3, 0, 0, 0, 7, 0, 0,10, 0, 0,13, 0, 0, 0,17, 0, 0
%p A154724 for n from 1 to 10 do for k from 1 to 2*n-1 do if(k=n or (isprime(k) and isprime(2*n-k)))then print(k):else print(0):fi:od:od: # _Nathaniel Johnston_, Apr 18 2011
%t A154724 Flatten@Table[If[k == n  || ( PrimeQ[k] && PrimeQ[2 n - k]), k, 0], {n, 10}, {k, 2 n - 1}] (* _Robert Price_, Apr 26 2025 *)
%Y A154724 Cf. A000040, A154720-A154727.
%K A154724 easy,nonn,tabf
%O A154724 1,3
%A A154724 _Omar E. Pol_, Jan 14 2009