A064475 Number of odd terms among first n terms of A064413 (if it begins at 2).

0, 0, 0, 1, 2, 2, 2, 2, 3, 4, 4, 4, 5, 6, 6, 6, 6, 6, 7, 8, 9, 9, 10, 11, 11, 11, 12, 13, 13, 13, 13, 14, 15, 15, 15, 16, 17, 18, 18, 18, 18, 19, 20, 20, 20, 20, 20, 20, 21, 22, 22, 23, 24, 24, 24, 25, 26, 26, 26, 27, 28, 28, 28, 28, 28, 29, 30, 31, 31, 31

Offset

2,5

Links

Table of n, a(n) for n=2..71.

J. C. Lagarias, E. M. Rains and N. J. A. Sloane, The EKG sequence, arXiv:math/0204011 [math.NT], 2002; Exper. Math. 11 (2002), 437-446.

Index entries for sequences related to EKG sequence

Mathematica

ekg[s_] := Block[{m = s[[-1]], k = 3}, While[MemberQ[s, k] || GCD[m, k] == 1, k++]; Append[s, k]];
EKG = Nest[ekg, {1, 2}, 71] ;
a[n_] := Count[EKG[[2 ;; n]], _?OddQ];
Table[a[n], {n, 2, 71}] (* Jean-François Alcover, Jan 11 2019, after Robert G. Wilson v in A064413 *)

Crossrefs

See A064952 for better version.

Sequence in context: A064775 A260731 A194239 * A025774 A280168 A001156

Adjacent sequences: A064472 A064473 A064474 * A064476 A064477 A064478

Keyword

nonn

Author

N. J. A. Sloane, Oct 05 2001

Status

approved