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 A178996 #15 Jan 27 2021 05:14:47
%S A178996 3,10,19,24,28,61,79,96,104,125,132,191,196,243,292,302,462,466,586,
%T A178996 621,1508,3307,3823,4729,5370,6721,8110,11145,13502,13762,20266,27868,
%U A178996 38522,75470
%N A178996 Numbers n such that 5^n mod 2^n is prime.
%C A178996 Here 'mod' denotes the binary modulo operation (nonnegative remainder).
%t A178996 fQ[n_] := PrimeQ@ PowerMod[5, n, 2^n]; k = 1; lst = {}; While[k < 17501, If[fQ@ k, AppendTo[lst, k]]; k++]; lst
%o A178996 (PARI) for(n=1,9999, ispseudoprime(5^n % 2^n) & print1(n",")) \\ _M. F. Hasler_, Jan 03 2011
%o A178996 (PARI) for(n=1,1e5,if(ispseudoprime(lift(Mod(5,2^n)^n)),print1(n", "))) \\ _Charles R Greathouse IV_, Oct 10 2011
%Y A178996 Cf. A178995.
%K A178996 nonn,hard
%O A178996 1,1
%A A178996 _Robert G. Wilson v_, Jan 03 2011
%E A178996 a(31)-a(34) from _Charles R Greathouse IV_, Oct 10 2011