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 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

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Last modified December 7 10:26 EST 2022. Contains 358656 sequences. (Running on oeis4.)