This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A176172 3rd prime-factor of n-th product of 4 distinct primes. 2
 5, 5, 5, 7, 5, 7, 5, 5, 7, 7, 7, 11, 5, 7, 5, 7, 5, 11, 7, 7, 7, 5, 11, 5, 7, 13, 7, 7, 5, 11, 13, 11, 7, 5, 7, 7, 5, 7, 13, 7, 5, 11, 11, 17, 7, 7, 11, 5, 7, 11, 11, 5, 11, 7, 5, 13, 7, 13, 17, 5, 7, 13, 11, 13, 7, 5, 11, 7, 7, 11, 19, 5, 11, 11, 7, 11, 7, 13, 5, 11, 17, 7, 13, 11, 7, 5, 7, 7, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS FactorInteger[210]=2*3*5*7,... LINKS Robert Israel, Table of n, a(n) for n = 1..10000 MAPLE N:= 10000: # to use products <= N Primes:= select(isprime, [2, seq(i, i=3..N/30)]): P4:= NULL: for ia from 1 to nops(Primes) do   a:= Primes[ia];   for ib from 1 to ia-1 do     b:= Primes[ib];     if 6*a*b > N then break fi;     for ic from 1 to ib-1 do       c:= Primes[ic];       if 2*a*b*c > N then break fi;       for id from 1 to ic-1 do         d:= Primes[id];         if a*b*c*d > N then break fi;         R[a*b*c*d]:= b;         P4:= P4, a*b*c*d; od od od od: P4:= sort([P4]): map(t -> R[t], P4); # Robert Israel, May 14 2019 MATHEMATICA f0[n_]:=Last/@FactorInteger[n]=={1, 1, 1, 1}; f1[n_]:=Min[First/@FactorInteger[n]]; f2[n_]:=First/@FactorInteger[n][[2, 1]]; f3[n_]:=First/@FactorInteger[n][[3, 1]]; f4[n_]:=Max[First/@FactorInteger[n]]; lst={}; Do[If[f0[n], AppendTo[lst, f3[n]]], {n, 0, 2*7!}]; lst CROSSREFS Cf. A006881, A007304, A070647, A096916, A096917, A096918, A096919, A176170, A176171 Sequence in context: A127934 A205236 A266948 * A204911 A087516 A194428 Adjacent sequences:  A176169 A176170 A176171 * A176173 A176174 A176175 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, Apr 10 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 12 07:00 EST 2019. Contains 329948 sequences. (Running on oeis4.)