OFFSET
1,1
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
Will Nicholes, Prime Signatures
MATHEMATICA
f[n_]:=Sort[Last/@FactorInteger[n]]=={1, 1, 1, 4}; Select[Range[15000], f]
Take[Union[First[#]^4 Times@@Rest[#]&/@Flatten[ Permutations/@ Subsets[ Prime[Range[20]], {4}], 1]], 50] (* Harvey P. Dale, Jan 26 2013 *)
PROG
(PARI) list(lim)=my(v=List(), t1, t2, t3); forprime(p=2, sqrtnint(lim\30, 4), t1=p^4; forprime(q=2, lim\(6*t1), if(q==p, next); t2=q*t1; forprime(r=2, lim\(2*t2), if(r==p || r==q, next); t3=r*t2; forprime(s=2, lim\t3, if(s==p || s==q || s==r, next); listput(v, t3*s))))); Set(v) \\ Charles R Greathouse IV, Aug 25 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Jul 24 2010
STATUS
approved