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 A273092 #21 Sep 08 2022 08:46:16
%S A273092 0,1,3,7,51,13,36,721,552,115,3201,7402,5904,1918,38361,76723,53556,
%T A273092 170131,341262,782425,5758401,1517902,3034914,7068838,51277761,
%U A273092 13445533,36880176,727712431,554534862,119078635,3281473701,7463847412,5927694924,1954399858
%N A273092 a(n) = 2^n - 1 written backwards.
%C A273092 Reverse primes in this sequence (3, 7, 31, 127, 2047, 8191, 131071, 524287, 8388607 etc) are Mersenne primes.
%H A273092 Vincenzo Librandi, <a href="/A273092/b273092.txt">Table of n, a(n) for n = 0..1000</a>
%F A273092 a(n) = A004086(A000225(n)).
%e A273092 For n = 8, 2^n - 1 = 255, so 552 is in the sequence. - _Michael B. Porter_, Jul 02 2016
%t A273092 Table[FromDigits[Reverse[IntegerDigits[2^n-1]]], {n, 0, 75}]
%o A273092 (Magma) [Seqint(Reverse(Intseq(2^n-1))): n in [0..40]];
%o A273092 (PARI) a(n) = eval(concat(Vecrev(Str(2^n-1)))) \\ _Felix Fröhlich_, Jul 03 2016
%Y A273092 Cf. A000225, A001348, A004086, A004087, A135623.
%K A273092 nonn,base,easy
%O A273092 0,3
%A A273092 _Vincenzo Librandi_, May 15 2016