This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A014950 #79 Jan 05 2025 19:51:34
%S A014950 1,3,9,27,81,111,243,333,729,999,2187,2997,4107,6561,8991,12321,13203,
%T A014950 19683,20439,26973,36963,39609,59049,61317,80919,110889,118827,151959,
%U A014950 177147,183951,242757,332667,356481,455877,488511,531441,551853,728271
%N A014950 Numbers m such that m divides 10^m - 1.
%C A014950 Also, m such that m | R(m) = A002275(m). - _Lekraj Beedassy_, Mar 25 2005
%C A014950 For n > 1, 3 divides a(n). If m is in the sequence and d divides m then for each positive integer k, d^k*m is in the sequence. So if m is in the sequence then m^k is in the sequence for each positive integer k. In particular, 3^k is in this sequence for all k. - _Farideh Firoozbakht_, Apr 14 2010
%C A014950 Numbers m such that m divides s(m), where s(1) = 1, s(k) = s(k-1) + k*10^(k-1).
%C A014950 Number of terms <= 10^k, beginning with k = 0: 1, 3, 5, 10, 15, 25, 41, 68, 108, 178, 291, ... - _Robert G. Wilson v_, Nov 30 2013
%C A014950 Numbers m such that m divides A033713(m). - _Hans Havermann_, Jan 25 2014
%D A014950 J. D. E. Konhauser et al., Which Way Did The Bicycle Go? Problem 80 pp. 26; 133, Dolciani Math. Exp., No. 18, MAA, Washington DC, 1996.
%H A014950 Hans Havermann, <a href="/A014950/b014950.txt">Table of n, a(n) for n = 1..1600</a> (first 800 terms from Robert G. Wilson v)
%H A014950 C. Cooper and R. E. Kennedy, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/27-2/kennedy.pdf">Niven Repunits and 10^n = 1 (mod n)</a>, The Fibonacci Quarterly, pp. 139-143, vol 27, May 02 1989.
%H A014950 Hans Havermann, <a href="http://chesswanks.com/seq/a014950.txt">A014950 factorized and atomized</a>.
%F A014950 Solutions to 10^m == 1 (mod m). - _Vladeta Jovovic_
%t A014950 Select[ Range[3, 1000000, 6], PowerMod[10, #, #] == 1 &] (* modified by _Robert G. Wilson v_, Dec 03 2013 *)
%t A014950 k = 3; A014950 = {1}; While[k < 1000000, If[ PowerMod[ 10, k, k] == 1, AppendTo[ A014950, k]; Print@ k]; k += 6]; A014950 (* _Robert G. Wilson v_, Nov 29 2013 *)
%o A014950 (PARI) is(n)=Mod(10,n)^n==1 \\ _Charles R Greathouse IV_, Nov 29 2013
%Y A014950 Cf. A066364, A114207, A122787, A127100, A232769.
%K A014950 nonn
%O A014950 1,2
%A A014950 _Olivier Gérard_
%E A014950 More terms from _Vladeta Jovovic_, Dec 18 2001
%E A014950 More terms from Larry Reeves (larryr(AT)acm.org), Jan 06 2005
%E A014950 Edited by _Max Alekseyev_, May 20 2011