OFFSET
1,1
COMMENTS
It would be nice to have a definition for this sequence which was independent of A254077.
From John Mason, Apr 15 2015: (Start)
Apparently, taking into account the first 675025 terms, corresponding to the first 20 million terms of A254077, a(n) divided by n-th prime A000040(n) is converging to 2. Here is the tail of this calculation:
n a(n) prime ratio
675016 19999695 10167763 1.966971004
675017 19999723 10167779 1.966970663
675018 19999766 10167799 1.966971023
675019 19999771 10167803 1.966970741
675020 19999787 10167809 1.966971154
675021 19999790 10167811 1.966971062
675022 19999903 10167881 1.966968634
675023 19999974 10167917 1.966968652
675024 19999985 10167919 1.966969347
675025 19999988 10167923 1.966968869
(End)
From John Mason, May 26 2016: (Start)
With respect to the previous observation, apparently, taking into account the first 26694011 terms, corresponding to the first 10^9 terms of A254077, a(n) divided by n-th prime A000040(n) is converging to just under 2. Here is the tail of this calculation:
n a(n) prime ratio
26694004 999999729 506784809 1.9732235679542636
26694005 999999770 506784833 1.9732235554097570
26694006 999999827 506784857 1.9732235744368345
26694007 999999857 506784881 1.9732235401868667
26694008 999999915 506784917 1.9732235144638293
26694009 999999941 506784919 1.9732235579804220
26694010 999999946 506784923 1.9732235522720947
26694011 999999967 506784937 1.9732235391992323
(End)
LINKS
Ray Chandler and John P. Linderman, Table of n, a(n) for n = 1..42315 [First 10000 terms from Ray Chandler]
John Mason, The first 675025 terms (zipped file)
MATHEMATICA
f[n_] := Block[{s = Range@ n, j, k}, For[k = 4, k <= n, k++, j = 4; While[Nand[GCD[j, s[[k - 2]]] > GCD[j, s[[k - 1]]], !MemberQ[Take[s, k - 1], j]], j++]; s[[k]] = j]; s]; Position[f@ 500, _?PrimeQ] // Flatten (* Michael De Vlieger, Apr 15 2015 *)
PROG
(Haskell)
a256213 n = a256213_list !! (n-1)
a256213_list = filter ((== 1) . a010051' . a254077) [1..]
-- Reinhard Zumkeller, May 05 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 26 2015
STATUS
approved