A193992 Position where 10^n-1 occurs in the Kaprekar sequence A006886.

2, 5, 8, 17, 24, 54, 62, 91, 102, 132, 149, 264, 281, 316, 385, 503, 527, 762, 790, 1035, 1154, 1278, 1378, 2304, 2374, 2498, 2575, 3122, 3910, 11330, 11714, 15400, 15478, 15642, 16039, 17892, 17909, 17968, 18401, 22238, 23747, 38524, 38728, 40625, 41101

Offset

1,1

Comments

Partial sums of A194232.

The Mathematica code computes 50 terms, but only these 45 terms are correct.

Links

Hans Havermann, Table of n, a(n) for n = 1..196

Index entries for Colombian or self numbers and related sequences

Mathematica

Inv[a_, b_] := PowerMod[a, -1, b]; t = {1}; Do[h = 10^k-1; d = Divisors[h]; d2 = Select[d, GCD[#, h/#] == 1 &]; AppendTo[t, h]; Do[AppendTo[t, d2[[i]]*Inv[d2[[i]], h/d2[[i]]]], {i, 2, Length[d2]-1}], {k, 50}]; t = Union[t]; Table[Position[t, 10^n-1, 1, 1][[1, 1]], {n, Log[10, t[[-1]]]}]

Crossrefs

Cf. A006886, A194232.

Sequence in context: A216307 A176223 A006827 * A112346 A062318 A034445

Adjacent sequences: A193989 A193990 A193991 * A193993 A193994 A193995

Keyword

nonn,base

Author

T. D. Noe, Aug 17 2011

Status

approved