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A193992 Position where 10^n-1 occurs in the Kaprekar sequence A006886. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 8 09:32 EST 2019. Contains 329862 sequences. (Running on oeis4.)