OFFSET
1,2
COMMENTS
Row widths: A004738(n): 1, 2, 1, 2, 3, 2, 1, 2, 3, 4, 3, 2, 1, 2, 3, 4, 5...
Pits: A051925(n+1): 0, 3, 11, 26, 50, 85, 133, 196, 276, 375, 495, 638...
Peak tops: A007290(n+3): 2, 8, 20, 40, 70, 112, 168, 240, 330, 440, 572...
Peak bases: A084990(n+1): 1, 6, 17, 36, 65, 106, 161, 232, 321, 430, 561...
EXAMPLE
The sequence of triangles begins:
0
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
PROG
(Python)
curSign=-1
curLength=sum=0
rowLength=topLength=1
for n in range(1232):
sum += n
curLength += 1
if curLength==rowLength:
print(sum, end=', ')
curLength = sum = 0
if rowLength==1 or rowLength==topLength:
curSign = -curSign
topLength += (rowLength==1)
rowLength += curSign
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alex Ratushnyak, Jun 28 2012
STATUS
approved