OFFSET
1,2
COMMENTS
a(n) = all values of A007955(m) in increasing order; all terms of sequence A007955 occur only once. Complement of A174896(n). A174897(a(n)) = 1, A174898(a(n)) = 0.
For every prime p, p and p^3 occur, as does the square of every semiprime pq with p and q distinct. - T. D. Noe, Oct 22 2010
For every prime p, every power p^t occurs, where t is a triangular number.
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
MATHEMATICA
nn=1000; Reap[Do[prod=Times@@Divisors[n]; If[prod<=nn, Sow[prod]], {n, nn}]][[2, 1]] (* T. D. Noe, Oct 22 2010 *)
PROG
(PARI) list(lim)=my(v=List(primes([2, lim]))); for(k=1, sqrtint(lim\=1), listput(v, factorback(divisors(k)))); forprime(p=2, sqrtnint(lim, 3), listput(v, p^3)); select(k->k<=lim, Set(v)) \\ Charles R Greathouse IV, Sep 22 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Apr 01 2010
EXTENSIONS
Corrected by Jaroslav Krizek, Apr 02 2010
Corrected and extended by T. D. Noe, Oct 22 2010
STATUS
approved