OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
R. Munafo, Generalized Cullen and Woodall Numbers
FORMULA
a(n) = 2n^2 - O(n^(5/3)). - Charles R Greathouse IV, Feb 19 2017
EXAMPLE
8=2*2^2. 24=3*2^3. 375=3*5^3.
PROG
(PARI) is(n)=if(n<8, return(0)); for(a=2, logint(n\2, 2), if(n%a==0 && ispower(n/a, a), return(1))); 0 \\ Charles R Greathouse IV, Feb 19 2017
(PARI) list(lim)=my(v=List()); if(lim<8, return([])); for(a=2, logint(lim\2, 2), for(b=2, sqrtnint(lim\a, a), listput(v, a*b^a))); Set(v) \\ Charles R Greathouse IV, Feb 19 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Munafo, Dec 12 2009
STATUS
approved