A triangle with rows containing the numbers that begins with 1, ends with n, and such that the sum of each two consecutive entries being a prime. Rows 2 to 6 are unique,

(Sloane's A051237) but there are multiple possibilities starting with row 7. For example, the two possibilities for row 7 are and . The number of possible rows ending with n = 1, 2, ..., are 0, 1, 1, 1, 1, 1, 2, 4, 7, 24, 80, ... (Sloane's A036440).

Pascal's Triangle