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 A221860 #25 Dec 23 2024 14:53:43 %S A221860 1,2,3,15,39,2119,4189897,5812974437 %N A221860 Indices k such that prime(k) - k is a power of 2. %C A221860 The only primes in this sequence below primepi(10^8) are 2, 3 and 4189897. %C A221860 prime(5812974437) - 5812974437 = 2^37. - _Giovanni Resta_, Apr 10 2013 %C A221860 a(9) > 1.4*10^16, if it exists. - _Chai Wah Wu_, Apr 24 2018 %H A221860 <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2013-April/011029.html">Re: 2^k - prime(p) or prime(p) - 2^k ?</a>, SeqFan mailing list, Apr 10 2013 %F A221860 A000040(a(n))-a(n) = 2^floor(log[2](A000040(a(n)))) for all n>1. %o A221860 (PARI) n=0;forprime(p=1,10^8,n++;(t=p-n)==1<<valuation(t,2)&print1(n",")) %Y A221860 Cf. A014689. %K A221860 nonn,more %O A221860 1,2 %A A221860 _M. F. Hasler_, Apr 10 2013 %E A221860 a(8) from _Giovanni Resta_, Apr 10 2013