Graph sequence thing

pips.py

def run(G, n):
    for _ in range(n):
        i = len(G[0]) - 1
        for j in range(len(G)):
            s = 0
            if 0 <= j - 1:
                s += G[j - 1][i]
            if j + 1 < len(G):
                s += G[j + 1][i]
            G[j] += (s, )
    return ((x for x in seq if x != 0) for seq in G)

def output(k, n):
    G = [(1,)] + [(0,)] * (k - 1)
    for seq in run(G, n):
        print(', '.join(map(str, seq)))

output(5, 20)