Floyd's triangle

Floyd's triangle is a right-angled triangular array of natural numbers, used in computer science education. It is named after Robert Floyd. It is defined by filling the rows of the triangle with consecutive numbers, starting with a 1 in the top left corner:

Beginning programmers are often assigned the task of writing a program to print out the table in the format shown.

The numbers along the left edge of the triangle are the lazy caterer's sequence and the numbers along the right edge are the triangular numbers. The nth row sums to , the constant of an  magic square .

Summing up the row sums in Floyd's triangle reveals the doubly triangular numbers (triangular numbers with an index that is triangular)
1               = 1 = T(T(1))                                                                                        

1                   = 6  = T(T(2))                                                                                                                                   
2  +  3

1 
2  +  3        =  21 = T(T(3))
4  +  5  +  6

See also      
Pascal's triangle

References

External links
Floyd's triangle at Rosetta code

Category:Triangles of numbers
Category:Computer programming
Category:Computer science education