pyprimes.html
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<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width,initial-scale=1" />
<title>Python (PyScript+MicroPython) Primes Maker</title>
<link rel="stylesheet" href="https://pyscript.net/releases/2026.3.1/core.css" />
<script type="module" src="https://pyscript.net/releases/2026.3.1/core.js"></script>
<style>
#numbers div { display: inline; }
</style>
</head>
<body>
<div id="numbers"></div>
<button id="button">Make more...</button>
<script type="mpy">
# Source - https://stackoverflow.com/a/568618
# Posted by Eli Bendersky, modified by community. See post 'Timeline' for change history
# Retrieved 2026-04-09, License - CC BY-SA 4.0
# Sieve of Eratosthenes
# Code by David Eppstein, UC Irvine, 28 Feb 2002
# http://code.activestate.com/recipes/117119/
def gen_primes():
""" Generate an infinite sequence of prime numbers.
"""
# Maps composites to primes witnessing their compositeness.
# This is memory efficient, as the sieve is not "run forward"
# indefinitely, but only as long as required by the current
# number being tested.
#
D = {}
# The running integer that's checked for primeness
q = 2
while True:
if q not in D:
# q is a new prime.
# Yield it and mark its first multiple that isn't
# already marked in previous iterations
#
yield q
D[q * q] = [q]
else:
# q is composite. D[q] is the list of primes that
# divide it. Since we've reached q, we no longer
# need it in the map, but we'll mark the next
# multiples of its witnesses to prepare for larger
# numbers
#
for p in D[q]:
D.setdefault(p + q, []).append(p)
del D[q]
q += 1
def take(g, n):
return [next(g) for _ in range(n)]
N = 1000
from pyscript import display, when
primes = gen_primes()
display(", ".join("%s" % p for p in take(primes, N)), target="#numbers")
@when("click", "#button")
def more_primes():
display(", " + (", ".join("%s" % p for p in take(primes, N))), target="#numbers")
</script>
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