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 A073814 a(n) is the smallest number k such that A073813(k) = prime(n). 0
 2, 4, 15, 33, 90, 129, 227, 288, 429, 694, 798, 1149, 1417, 1565, 1879, 2399, 2993, 3201, 3879, 4365, 4623, 5429, 6002, 6920, 8245, 8948, 9314, 10067, 10457, 11245, 14251, 15184, 16627, 17130, 19711, 20253, 21919, 23653, 24845, 26687, 28604, 29248, 32612, 33303, 34719, 35436, 39893, 44622, 46254 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA Min{x; c[x]-Max[URS[c[x]]]=p(n)}, p(n)=n-th prime. See program. EXAMPLE a(6)=129 means that c[129]-Max[URS[c[129]]=Prime[6]: c[129]=169, Max[URS[169]]=Max{26,39,...,143,156}=156; difference=169-156=13=6th prime. Suspicion: A073813(n) is always prime number! MATHEMATICA c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x]; tn[x_] := Table[j, {j, 1, x}]; di[x_] := Divisors[x]; rrs[x_] := Flatten[Position[GCD[tn[x], x], 1]]; rs[x_] := Union[rrs[x], di[x]]; urs[x_] := Complement[tn[x], rs[x]]; Do[s=c[n]-Max[urs[c[n]]]; If[s<101&&t[[s]]==0, t[[s]]=n], {n, 1, 10}]; t nn = 6 * 10^4; s = Function[k, k - SelectFirst[Range[k - 2, 2, -1], 1 < GCD[#, k] < # &]] /@ Select[Range[6, nn], ! PrimeQ@ # &]; Table[SelectFirst[Range@ Length@ s, s[[# - 1]] == Prime@ n &], {n, 49}] (* Michael De Vlieger, Mar 28 2016, Version 10 *) CROSSREFS Cf. A045763, A073759, A002808, A073813. Cf. A120389. [From R. J. Mathar, Aug 07 2008] Sequence in context: A260299 A080623 A196260 * A181442 A007122 A005219 Adjacent sequences:  A073811 A073812 A073813 * A073815 A073816 A073817 KEYWORD nonn AUTHOR Labos Elemer, Aug 15 2002 EXTENSIONS Definition corrected by Gionata Neri, Mar 28 2016 More terms from Michael De Vlieger, Mar 28 2016 STATUS approved

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Last modified April 22 13:29 EDT 2021. Contains 343177 sequences. (Running on oeis4.)