PASCAL’S TRIANGLE
the first thirteen rows, the sum of each row and the pattern of the odd numbers
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
Rows are numbered from zero, and row n holds n + 1 numbers. To learn in how many ways k things can be chosen out of n, take row n and count k places along it, again from zero. The number of each row stands to its left, and the sum of all its numbers to its right.