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A064423 Position of n-th prime in A064413 (if it begins at 2).

%I A064423 #15 Sep 02 2018 01:40:46
%S A064423 1,4,9,13,19,27,32,36,42,56,60,66,73,80,88,99,106,114,127,133,137,150,
%T A064423 159,166,181,188,196,202,206,215,235,252,258,263,278,286,296,304,313,
%U A064423 327,335,343,362,370,376,380,400,419,429,437,443,457,461,473,486,500,509,516,529,539,548,556,580,586,598,605,628,638,654,663,669,680,698,706,723,729,735,755,765,780,797,801,813,818,832,847,856,873,881,888,897,910,926,941,952,960,970,996,1003,1028,1040,1058,1071,1079,1086,1098,1117,1134,1141,1149,1155,1174,1180,1189,1202,1222,1231,1241,1248,1257,1265,1286,1297,1305,1323,1349,1356,1377,1390,1397,1409,1424,1432,1441,1455,1469,1477,1503,1515,1541,1545,1563,1567,1577,1585,1609,1625,1637,1645,1651,1679,1685,1692,1701,1733,1738,1759
%N A064423 Position of n-th prime in A064413 (if it begins at 2).
%C A064423 It can be shown that this sequence is monotonic.
%H A064423 T. D. Noe, <a href="/A064423/b064423.txt">Table of n, a(n) for n = 1..1000</a>
%H A064423 J. C. Lagarias, E. M. Rains and N. J. A. Sloane, <a href="https://arxiv.org/abs/math/0204011">The EKG sequence</a>, arXiv:math/0204011 [math.NT], 2002.
%H A064423 J. C. Lagarias, E. M. Rains and N. J. A. Sloane, <a href="https://projecteuclid.org/euclid.em/1057777433">The EKG sequence</a>, Exper. Math. 11 (2002), 437-446.
%H A064423 <a href="/index/Ed#EKG">Index entries for sequences related to EKG sequence</a>
%t A064423 terms = 100;
%t A064423 ekg[s_] := Block[{m = s[[-1]], k = 3}, While[MemberQ[s, k] || GCD[m, k] == 1, k++]; Append[s, k]];
%t A064423 EKG = Nest[ekg, {2, 4}, 12 terms];
%t A064423 a[n_] := FirstPosition[EKG, Prime[n]][[1]];
%t A064423 Array[a, terms] (* _Jean-François Alcover_, Sep 02 2018, after _Robert G. Wilson v_ in A064413 *)
%Y A064423 Cf. A064413, A064425. See A064955 for better version.
%K A064423 nonn,nice
%O A064423 1,2
%A A064423 _N. J. A. Sloane_, Sep 30 2001
%E A064423 More terms from _Vladeta Jovovic_, Oct 01 2001