{ "cells": [ { "cell_type": "markdown", "id": "1b6c514b", "metadata": {}, "source": [ "# [Distinct Primes Factors](https://projecteuler.net/problem=47)\n", "\n", "The [prime omega function](https://en.wikipedia.org/wiki/Prime_omega_function) $\\omega(n)$ counts the number of distinct prime factors of $n$. SageMath provides this function through the [PARI/GP interface](https://doc.sagemath.org/html/en/reference/interfaces/sage/interfaces/gp.html), but we can also just look at the length of the output of the built-in `factor` function.\n", "\n", "See [problem 3](https://projecteuler.net/problem=3) for information on implementing a factorization function." ] }, { "cell_type": "code", "execution_count": 1, "id": "49b0126c", "metadata": {}, "outputs": [ { "data": { "text/plain": [ "134043" ] }, "execution_count": 1, "metadata": {}, "output_type": "execute_result" } ], "source": [ "from itertools import count\n", "\n", "def omega(n):\n", " return len(factor(n))\n", "\n", "\n", "for n in count(1):\n", " if all(omega(n+k) == 4 for k in (0,1,2,3)):\n", " break\n", "\n", "n" ] }, { "cell_type": "markdown", "id": "ebcdb94b", "metadata": {}, "source": [ "## Relevant sequences\n", "* Number of distinct prime factors: [A001221](https://oeis.org/A001221)\n", "\n", "#### Copyright (C) 2025 filifa\n", "\n", "This work is licensed under the [Creative Commons Attribution-ShareAlike 4.0 International license](https://creativecommons.org/licenses/by-sa/4.0/) and the [BSD Zero Clause license](https://spdx.org/licenses/0BSD.html)." ] } ], "metadata": { "kernelspec": { "display_name": "SageMath 9.5", "language": "sage", "name": "sagemath" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 3 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", "version": "3.11.2" } }, "nbformat": 4, "nbformat_minor": 5 }