A260594 a(n) is the least k such that A260590(k) = A260593(n).

1, 2, 3, 5, 13, 15, 19, 23, 35, 45, 51, 55, 63, 77, 79, 83, 95, 115, 119, 125, 141, 143, 179, 255, 319, 335, 351, 435, 463, 495, 527, 653, 791, 819, 847, 909, 1023, 1143, 1699, 1715, 2127, 2295, 3191, 3197, 3443, 3639, 3763, 3981, 5043, 6199, 6719, 7519, 8845

Offset: 1

Author

Joseph K. Horn and Robert G. Wilson v, Aug 30 2015

Keywords

• nonn
• easy

Comments

This is the index corresponding to, or responsible for, A260593.

Examples

			13 is the least k such that A260590(k) = 59 = A260593(5), so a(5) = 13.
		

Crossrefs

Cf. A260590, A260593.

Programs

Mathematica

msa[n_] := If[ OddQ@ n, (3n + 1)/2, n/2]; f[n_] := Block[{k = 2n + 1}, Length@ NestWhileList[ msa@# &, k, # >= k &] - 1]; k = 1; lst = lsu = {}; While[k < 10000001, a = f@ k; If[ !MemberQ[lst, a], AppendTo[lst, a]; AppendTo[lsu, k]]; k++]; lsu