The position of the first occurrence of n in A347249.

Terms

a(0) =1a(1) =15a(2) =25a(3) =75a(4) =275a(5) =725a(6) =2175a(7) =3725a(8) =9025a(9) =27075a(10) =79025a(11) =215905a(12) =390625a(13) =1079525a(14) =2256125a(15) =5397625a(16) =11328125a(17) =33984375a(18) =58203125a(19) =174609375