Okla. Stat. tit. 84, § 131

Whenever a testator has a child born after the making of his will, either in his lifetime or after his death, and dies leaving such child unprovided for by any settlement, and neither provided for nor in any way mentioned in his will, the child succeeds to the same portion of the testator's real and personal property that he would have succeeded to if the testator had died intestate.