Draw a descendant pyramid (addition)
Jelly, &nbsp;14&nbsp; 13 bytes

14 -> 13 assumes trailing spaces-only entry is allowed in the list format output; if not I shall revert to the 14 (asked)

+ƝƬK€z⁶Zṙ"JC$


A monadic link. Output is a list of lists using space characters as the spaces (includes a single trailing spaces-only entry).

Try it online! (includes a footer to show the list structure since running the monadic link as a full program will print smashed output implicitly.)