A179693 Numbers of the form p^4*q*r*s where p, q, r, and s are distinct primes.

1680, 2640, 3120, 3696, 4080, 4368, 4560, 5520, 5670, 5712, 6160, 6384, 6864, 6960, 7280, 7440, 7728, 8880, 8910, 8976, 9520, 9744, 9840, 10032, 10320, 10416, 10530, 10608, 10640, 11280, 11440, 11856, 12144, 12432, 12474, 12720, 12880, 13770

Offset

1,1

Links

T. D. Noe, Table of n, a(n) for n = 1..1000

Will Nicholes, Prime Signatures

Index to sequences related to prime signature

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

Sequence in context: A268288 A175749 A231548 * A290704 A342876 A175340

Adjacent sequences: A179690 A179691 A179692 * A179694 A179695 A179696

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Jul 24 2010

Status

approved