A134292 Triangle in which row n is the lexicographically earliest solution to the prime circle problem for 2n.

1, 2, 1, 2, 3, 4, 1, 4, 3, 2, 5, 6, 1, 2, 3, 8, 5, 6, 7, 4, 1, 2, 3, 4, 7, 6, 5, 8, 9, 10, 1, 2, 3, 4, 7, 6, 5, 12, 11, 8, 9, 10, 1, 2, 3, 4, 7, 6, 13, 10, 9, 14, 5, 8, 11, 12, 1, 2, 3, 4, 7, 6, 5, 12, 11, 8, 9, 14, 15, 16, 13, 10, 1, 2, 3, 4, 7, 6, 5, 8, 9, 10, 13, 16, 15, 14, 17, 12, 11, 18, 1, 2, 3

Offset: 1

Author

T. D. Noe, Oct 16 2007

Keywords

• nice
• nonn
• look
• tabf

Comments

In the prime circle problem we seek to arrange the numbers 1 to 2n around a circle so that the sum of each pair of adjacent numbers is prime. To display the solution, we unroll the circle starting at 1.

Examples

			Triangle begins:
1, 2;
1, 2, 3, 4;
1, 4, 3, 2, 5, 6;
1, 2, 3, 8, 5, 6, 7, 4;
...
		

References

• R. K. Guy, Unsolved Problems Number Theory, Section C1.

Links

• T. D. Noe, Rows n=1..50 of triangle, flattened
• Eric Weisstein's World of Mathematics, Prime Circle

Crossrefs

Cf. A051252 (number of solutions for each n), A051237 (prime pyramid).