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 A061157 #11 Jan 25 2023 22:06:43 %S A061157 11,22,37,74,109,151,247,253,337,382,403,506,509,547,674,739,764,779, %T A061157 806,1325,1478,1528,1558,1589,1597,1612,1871,1987,2263,2279,2317,2759, %U A061157 2797,3056,3116,3194,3329,3341,3719,3742,3761,3821,4001,4412,4526,4558,4559,4603,4736,4813 %N A061157 Numbers k such that k*2^m-1 is prime for exactly one exponent m in the range 0<=m<=k. %H A061157 Michael S. Branicky, <a href="/A061157/b061157.txt">Table of n, a(n) for n = 1..125</a> %Y A061157 Cf. A061153, A061154, A061155, A061156. See A066158 for exponents. %K A061157 nonn %O A061157 1,1 %A A061157 _Patrick De Geest_, Apr 15 2001 %E A061157 Offset corrected and more terms from _Sean A. Irvine_, Jan 24 2023