%I
%S 1,3,2,1,4,2,5,4,3,2,6,2,3,4,8,1,4,4,6,9,12,6,4,12,6,7,30,4,12,12,5,
%T 16,6,4,10,10,12,10,6,3,4,6,10,4,6,2,4,10,6,17,4,10,4,18,6,30,12,12,4,
%U 10,27,4,6,4,12,4,28,6,2,10,4,4,10,12,18,10,10,3,12,4,12,6,10,10,18,10,12
%N Difference between a nontrivial prime power (A025475) and the next prime.
%F a(n)=nextprime[A025475(n)]A025475(n)=A013632[A025475(n)]
%e 78125=5^7 is followed by 78137, the difference is 12; a(n)=1 only for some powers of 2.
%Y Cf. A025475, A000961, A001597, A001694, A007917, A007918, A013632, A013633, A049711.
%K nonn
%O 1,2
%A _Labos Elemer_, May 03 2001
