A101868 a(n) = n + 2*ceiling(phi*n), where phi = (1 + sqrt(5))/2. Row 1 of A101866.

5, 10, 13, 18, 23, 26, 31, 34, 39, 44, 47, 52, 57, 60, 65, 68, 73, 78, 81, 86, 89, 94, 99, 102, 107, 112, 115, 120, 123, 128, 133, 136, 141, 146, 149, 154, 157, 162, 167, 170, 175, 178, 183, 188, 191, 196, 201, 204, 209, 212, 217, 222, 225, 230, 233, 238, 243, 246, 251, 256

Offset: 1

Author

N. J. A. Sloane, Jan 28 2005

Keywords

• nonn

Comments

Positions of 1 in A188009 = (0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0,...)

A101868 = (5, 10, 13, 18, 23, 26, 31, 34, 39, 44, 47, 52, 57, 60, ...). - Clark Kimberling, Mar 19 2011, corrected by M. F. Hasler, Oct 12 2017

Essentially the same as A188434, which has an initial 2 prefixed. However, the present sequence would have a(0) = 0 if extended to offset / index 0. - M. F. Hasler, Oct 12 2017

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A188009, A101868, A188434.

Cf. A001622, A101866.

Programs

Mathematica

Array[# + 2*Ceiling[#*GoldenRatio] &, 100] (* Paolo Xausa, Mar 20 2024 *)

PARI

a(n)=n+2*ceil(quadgen(5)*n+.) \\ M. F. Hasler, Oct 12 2017