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 A139768 Numbers n such that (10^(n+1) mod 9^(n+1))/(10^n mod 9^n)=10, or A139739(n+1)/A139739(n)=10. 2
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Also, this is the set of numbers n such that 9*floor((10/9)^(n+1))==10*floor((10/9)^n) (cf. A065566). For proof see Mathar link. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 R. J. Mathar, Proof of alternative characterization. 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 CROSSREFS Cf. A139739, A065566. Sequence in context: A224701 A050782 A061906 * A307278 A176071 A072708 Adjacent sequences:  A139765 A139766 A139767 * A139769 A139770 A139771 KEYWORD nonn AUTHOR Zak Seidov and N. J. A. Sloane, May 20 2008, May 24 2008 STATUS approved

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Last modified August 10 19:52 EDT 2020. Contains 336381 sequences. (Running on oeis4.)