A258049 Position of n in A258047 after deleting the initial 0.

1, 2, 4, 5, 7, 9, 11, 14, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 36, 38, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125

Offset: 1

Author

Clark Kimberling, Jun 05 2015

Keywords

• nonn
• easy

Comments

A258047 = (0,1,2,-1,3,6,-7,5,-3,7,...). Remove the initial 0 to get (1,2,-1,3,6,-7,5,6,-3,7,...), and note that (1,2,3,4,...) occupy positions 1,2,4,7,..., (as in A258049) and that (-1,-2,-3,...) occupy positions 3,6,8,... (as in A258050).

Links

• Clark Kimberling, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A258047, A258050 (complement).

Programs

Mathematica

{a, f} = {{1}, {0}}; Do[tmp = {#, # - Last[a]} &[Min[Complement[#, Intersection[a, #]]&[Last[a] + Complement[#, Intersection[f, #]] &[Range[2 - Last[a], -1]]]]];
If[! IntegerQ[tmp[[1]]], tmp = {Last[a] + #, #} &[NestWhile[# + 1 &, 1, ! (! MemberQ[f, #] && ! MemberQ[a, Last[a] - #]) &]]];
AppendTo[a, tmp[[1]]]; AppendTo[f, tmp[[2]]], {500}];
-1 + Flatten[Position[Sign[f], 1]] (* A258049 *)
-1 + Flatten[Position[Sign[f], -1]] (* A258050 *) (* Peter J. C. Moses, May 14 2015 *)