A139768 Numbers k such that (10^(k+1) mod 9^(k+1))/(10^k mod 9^k)=10, or A139739(k+1)/A139739(k)=10.
21, 38, 57, 58, 71, 81, 127, 148, 164, 181, 188, 195, 204, 208, 209, 212, 232, 244, 249, 250, 251, 252, 267, 269, 270, 300, 317, 326, 356, 357, 382, 398, 407, 409, 416, 417, 420, 447, 448, 453, 471, 479, 480, 481, 492, 502, 505, 528, 530, 548, 554, 561, 570
Offset: 1
Keywords
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
- R. J. Mathar, Proof of alternative characterization.
Programs
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Maple
Res:= NULL: count:= 0: v:= 1: for n from 2 while count < 100 do u:= floor((10/9)^n); if 9*u = 10*v then count:= count+1; Res:= Res, n-1 fi; v:= u; od: Res; # Robert Israel, Jul 10 2018
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Mathematica
Select[Range[570],(Mod[10^(#+1),9^(#+1)]/Mod[10^#,9^#])==10&] (* James C. McMahon, Jul 05 2025 *)
Comments