A065519 a(n) = A064413(n)-n.

0, 0, 1, 2, -2, 3, 5, 0, 1, -5, 4, 6, 1, -7, 6, 8, -1, 2, 3, -9, 12, 5, 7, 1, 10, 2, -1, -15, 10, 6, 1, 2, -16, 17, 7, 2, -18, 19, 6, 0, 3, 4, -20, 25, 3, 4, 5, 6, 7, -1, 12, 8, 2, 11, 15, 2, -28, 29, 7, 2, -30, 31, 9, 0, 3, 8, -30, 43, 6, 8, 5, 8, 9

Offset: 1

Author

N. J. A. Sloane, Nov 28 2001

Keywords

• sign

Comments

Zeros appear at A152458.

Links

• Peter Kagey, Table of n, a(n) for n = 1..10000
• J. C. Lagarias, E. M. Rains and N. J. A. Sloane, The EKG sequence, arXiv:math/0204011 [math.NT], 2002.
• J. C. Lagarias, E. M. Rains and N. J. A. Sloane, The EKG Sequence, Exper. Math. 11 (2002), 437-446.
• Index entries for sequences related to EKG sequence

Crossrefs

Cf. A064413, A152458.

Programs

Mathematica

terms = 100;
ekg[s_] := Block[{m = s[[-1]], k = 3}, While[MemberQ[s, k] || GCD[m, k] == 1, k++]; Append[s, k]];
Nest[ekg, {1, 2}, terms-2] - Range[terms] (* Jean-François Alcover, Sep 10 2018, after Robert G. Wilson v *)