#[MATL](https://github.com/lmendo/MATL), 13 bytes ttn:2/k)>~4L) [Try it online!](http://matl.tryitonline.net/#code=dHRuOjIvayk-fjRMKQ&input=WzE2LCAxNCwgMTAsIDgsIDcsIDksIDMsIDIsIDQsIDFd) Or [verify all test cases at once](http://matl.tryitonline.net/#code=YAp0dG46Mi9rKT5-NEwpCkRU&input=WzkwLCAxNSwgMTAsIDcsIDEyLCAyXQpbOTMsIDE1LCA4NywgNywgMTUsIDVdClsxNiwgMTQsIDEwLCA4LCA3LCA5LCAzLCAyLCA0LCAxXQpbMTAsIDksIDgsIDcsIDYsIDUsIDQsIDMsIDIsIDFdClsxMDAsIDE5LCAzNiwgMTcsIDMsIDI1LCAxLCAyLCA3XQpbNSwgNSwgNSwgNSwgNSwgNSwgNSwgNV0KWzQsIDUsIDUsIDUsIDUsIDUsIDUsIDVdCls5MCwgMTUsIDEwLCA3LCAxMiwgMTFdClsxLCAyLCAzLCA0LCA1XQpbNCwgOCwgMTUsIDE2LCAyMywgNDJdClsyLCAxLCAzXQ). An array is truthy if it is non-empty and all its entries are nonzero. Otherwise it's falsy. Here are [some examples](http://matl.tryitonline.net/#code=YCAgICAgICAgICAgICUgaW5maW5pdGUgbG9vcCB0byB0YWtlIGFsbCBpbnB1dHMKPyd0cnV0aHknICAgICUgaWY6IHRydXRoeQp9J2ZhbHN5JyAgICAgJSBlbHNlOiBmYWxzeQpdICAgICAgICAgICAgJSBlbmQgaWYKRFQgICAgICAgICAgICUgZGlzcGxheSBhbmQgZW5kIGxvb3A&input=W10KWzAgMSAyXQpbMyA0IC01XQpbMSAxOyAxIDFd). ###Explanation t % Take input implicitly. Duplicate tn: % Duplicate and generate range [1 2 ...n] where n is input size 2/k % Divide by 2 and round down ) % Index into input. Gives array of parents, except for the first entry >~ % True for entries of the input that don't exceed those in the array of parents 4L) % Discard first entry