noindex paginated homepage for Genesis / Yoast

genesis.php

<?php
add_filter( 'genesis_get_robots_meta_content', 'sp_noindex_paginated_front_page' );
/**
 * No-index paginated front-page if Genesis SEO is in use.
 *
 * @param array $directives The robots directives.
 * @return array The directives with noindex set if on a paginated front page.
 */
function sp_noindex_paginated_front_page( $directives ) {
    if ( is_front_page() && is_paged() ) {
        $directives['noindex'] = 'noindex';
    }

    return $directives;
}

yoast.php

<?php
add_filter( 'wpseo_robots', 'sp_yoast_noindex_paginated_front_page' );
/**
 * No-index paginated homepage for Yoast SEO.
 *
 * @param string $robots Current robots meta value.
 * @return string Updated robots meta value.
 */
function sp_yoast_noindex_paginated_front_page( $robots ) {
    if ( ! ( is_front_page() && is_paged() ) ) {
        return $robots;
    }

    if ( '' === $robots ) {
        return 'noindex';
    }

    return $robots . ',noindex';
}