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Prime Triangle


A triangle with rows containing the numbers {1,2,...,n} 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,

 *
1  2
1  2  3
1  2  3  4
1  4  3  2  5
1  4  3  2  5  6

(OEIS A051237) but there are multiple possibilities starting with row 7. For example, the two possibilities for row 7 are {1,4,3,2,5,6,7} and {1,6,5,2,3,4,7}. The number of possible rows ending with n=1, 2, ..., are 0, 1, 1, 1, 1, 1, 2, 4, 7, 24, 80, ... (OEIS A036440).


See also

Pascal's Triangle

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References

Guy, R. K. Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, p. 106, 1994.Kenney, M. J. "Student Math Notes." NCTM News Bulletin. Nov. 1986.Sloane, N. J. A. Sequences A036440 and A051237 in "The On-Line Encyclopedia of Integer Sequences."

Referenced on Wolfram|Alpha

Prime Triangle

Cite this as:

Weisstein, Eric W. "Prime Triangle." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PrimeTriangle.html

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