%I #4 Mar 30 2012 18:50:43
%S 1,3,7,13,25,41,64,97,128,173,233,283,359,439,523,619,729,841,971,
%T 1093,1249,1423,1567,1733,1931,2113,2309,2531,2731,2969,3251,3499,
%U 3733,4019,4289,4621,4937,5237,5569,5881,6269,6637,6977,7417
%N Greatest number in the n-th successive group of natural numbers containing exactly n prime powers.
%C a(n) = A000961(A000217(n)).
%e 1 : 2 3 : 4 5 6 7 : 8 9 10 11 12 13 : 14 15 16 17 18 ...
%e 1 : 2 3 : 4 5 . 7 : 8 9 .. 11 .. 13 : .. .. 16 17 ...
%e 1 : . 3 : . . . 7 : . . .. .. .. 13 : .. .. ...
%e a(1)..a(2)......a(3).............a(4)......
%K nonn
%O 1,2
%A _Reinhard Zumkeller_, Mar 25 2004