Load this file into remix-ide (Realtime Ethereum Contract Compiler and Runtime) by pasting this gists URL or ID at https://remix.ethereum.org/#version=soljson-v0.6.9+commit.3e3065ac.js&optimize=false&gist=7f4de04ec5e3e926af27d5cd437aa8e2

stackExchange_85231_array-of-mapping.sol

// https://ethereum.stackexchange.com/questions/85231/array-of-mapping

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.5.0 <0.8.0;

contract myContract {
    
    mapping (address => mapping (uint => uint)) public payments;
    mapping (address => uint) public lastPayment;

    function sendMoney() public payable {
        require(msg.value > 0);
        payments[msg.sender][lastPayment[msg.sender]] = msg.value;
        lastPayment[msg.sender]++;
    }

}