Floyd's triangle

Floyd's triangle lists the natural numbers in a right triangle aligned to the left where

the first row is just 1
successive rows start towards the left with the next number followed by successive naturals listing one more number than the line above.

The first few lines of a Floyd triangle looks like this:

 1
 2  3
 4  5  6
 7  8  9 10
11 12 13 14 15

The task is to:

Write a program to generate and display here the first n lines of a Floyd triangle.
(Use n=5 and n=15 rows).
Ensure that when displayed in a monospace font, the numbers line up in vertical rows as shown and that only one space separates the two largest numbers.

Python

<lang python>>>> def floyd(rowcount=5): rows = 1 while len(rows) < rowcount: n = rows[-1][-1] + 1 rows.append(list(range(n, n + len(rows[-1]) + 1))) return rows

>>> floyd() [[1], [2, 3], [4, 5, 6], [7, 8, 9, 10], [11, 12, 13, 14, 15]] >>> def pfloyd(rows=[[1], [2, 3], [4, 5, 6], [7, 8, 9, 10]]): colspace = [len(str(n)) for n in rows[-1]] for row in rows: print( ' '.join('%*i' % space_n for space_n in zip(colspace, row)))

>>> pfloyd() 1 2 3 4 5 6 7 8 9 10 >>> pfloyd(floyd(8))

11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 >>> pfloyd(floyd(15))

 1
 2   3
 4   5   6
 7   8   9  10
11  12  13  14  15
16  17  18  19  20  21
22  23  24  25  26  27  28
29  30  31  32  33  34  35  36
37  38  39  40  41  42  43  44  45
46  47  48  49  50  51  52  53  54  55
56  57  58  59  60  61  62  63  64  65  66
67  68  69  70  71  72  73  74  75  76  77  78
79  80  81  82  83  84  85  86  87  88  89  90  91
92  93  94  95  96  97  98  99 100 101 102 103 104 105

106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 >>> </lang>