convolve.py

#!/usr/bin/env python3
import sys

def emit(order, unit):
    matrix = ('1 '*(order*order))[:-1]
    attrs = [
        f'order="{order}"',
        f'kernelMatrix="{matrix}"',
        'targetX="0"',
        'targetY="0"',
        f'kernelUnitLength="{unit}"',
    ]
    if unit == 1:
        attrs.insert(0, 'in="SourceGraphic"')
    print(f'<feConvolveMatrix {" ".join(attrs)}/>')

n = int(sys.argv[1])
unit = 1

fours = 0
while n % 4 == 0:
    n //= 4
    fours += 1
if n % 2 == 0:
    emit(2, unit)
    n //= 2
    unit *= 2
while n % 3 == 0:
    emit(3, unit)
    n //= 3
    unit *= 3
for _ in range(fours):
    emit(4, unit)
    unit *= 4

order = 5
while order*order <= n:
    if n % order == 0:
        emit(order, unit)
        n //= order
        unit *= order
    else:
        order += 2
if n != 1:
    emit(n, unit)