Prime powers (A025475) such that the distance to the nearest prime power is a prime.

Terms

a(0) =1a(1) =4a(2) =16a(3) =25a(4) =27a(5) =32a(6) =81a(7) =125a(8) =128a(9) =169a(10) =243a(11) =256a(12) =512a(13) =529a(14) =2048a(15) =7921a(16) =8192a(17) =32761a(18) =32768a(19) =130321a(20) =131072a(21) =134689a(22) =524288a(23) =2093809a(24) =2097152a(25) =8388608a(26) =8392609a(27) =134217728a(28) =134258569a(29) =536870912