PublicIpCopy.json

{
    "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {},
    "variables": {},
    "resources": [
        {
            "apiVersion": "2015-06-15",
            "type": "Microsoft.Network/publicIPAddresses",
            "name": "[concat('myPublicIp-', copyindex())]",
            "location": "[resourceGroup().location]",
             "copy": {
                "name": "publicIpLoop",
                "count": 3
            },
            "properties": {
                "publicIPAllocationMethod": "Dynamic"
            }
        }
    ],
    "outputs": { }
}