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 A161675 #10 Oct 22 2024 03:28:45 %S A161675 3,7,37,177,17777,377777,1777777,17777777777,177777777777777777777, %T A161675 377777777777777777777777777777,377777777777777777777777777777777777, %U A161675 1777777777777777777777777777777777777777777 %N A161675 Mersenne primes written in base 8. %H A161675 Amiram Eldar, <a href="/A161675/b161675.txt">Table of n, a(n) for n = 1..17</a> %F A161675 a(n) = A007094(A000668(n)). %t A161675 Map[FromDigits[IntegerDigits[2^# - 1, 8]] &, MersennePrimeExponent[Range[12]]] (* _Amiram Eldar_, Oct 22 2024 *) %Y A161675 Cf. A000668, A007094, A117293. %K A161675 nonn,base %O A161675 1,1 %A A161675 Vladislav-Stepan Malakhovsky & _Juri-Stepan Gerasimov_, Jun 16 2009 %E A161675 a(6) and a(10) corrected by _R. J. Mathar_, Aug 03 2009