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 A168158 #6 Apr 03 2023 10:36:11 %S A168158 7,10,11,12,15,18,29,35,45,49,51,55,58,65,80,82,84,89,93,95,114,119, %T A168158 128,130,140,142,149,155,157,160,166,171,173,175,191,192,209,210,218, %U A168158 235,240,251,262,263,269,280,305,315,321,324,328,337,341,344,345,363,372 %N A168158 Indices n for which A168157(n) is prime. %C A168158 If n=primepi(2^k-1) is in this sequence, then A158671(k) is prime. This happens for k=5, 6, 18,... corresponding to n=11, 18, 23000,... (cf. link). %H A168158 C. Caldwell, G. L. Honaker, Editors: <a href="https://t5k.org/curios/page.php?short=18&submitter=Post">Prime curio!: 18</a> by J. Vos Post. %o A168158 (PARI) s=0; for(n=1,999, isprime(n*#(b=binary(prime(n)))-s+=norml2(b)) & print1(n", ")) %K A168158 nonn %O A168158 1,1 %A A168158 _M. F. Hasler_, Nov 21 2009