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.

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, 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, 0, 5, 0, 7, 0, 9, 0, 11, 0, 13, 0, 0, 0, 0

Offset

1,3

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Example

Triangle begins:
                             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, 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, 0, 5, 0, 7, 0, 9, 0,11, 0,13, 0, 0, 0, 0
  0, 0, 3, 0, 0, 0, 7, 0, 0,10, 0, 0,13, 0, 0, 0,17, 0, 0

Maple

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

Crossrefs

Cf. A000040, A154720-A154727.

Sequence in context: A306078 A284273 A083927 * A232747 A130460 A132440

Adjacent sequences: A154721 A154722 A154723 * A154725 A154726 A154727

Keyword

easy,nonn,tabf

Author

Omar E. Pol, Jan 14 2009

Status

approved