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 A247856 #9 Feb 16 2025 08:33:23
%S A247856 3,1,3,2,3,3,0,8,0,9,8,6,9,4,5,9,1,2,6,3,0,7,8,6,4,8,6,4,7,2,1,7,2,8,
%T A247856 0,0,4,3,9,2,5,1,1,7,4,5,0,5,2,2,5,3,9,7,1,7,3,2,6,8,4,8,5,4,0,4,4,3,
%U A247856 1,4,5,9,0,8,5,0,2,0,1,0,3,6,8,3,6,9,3,8,1,0,8,9,1,2,6,2,6,7,6,9,8
%N A247856 Decimal expansion of the value of the continued fraction [0; 3, 5, 5, 7, 11, 13, 17, 19, ...] generated by twin primes.
%H A247856 Eric Weisstein's MathWorld, <a href="https://mathworld.wolfram.com/TwinPrimes.html">Twin Primes</a>
%H A247856 Marek Wolf, <a href="http://arxiv.org/abs/1003.4015">Continued fractions constructed from prime numbers</a>, arxiv.org/abs/1003.4015, p. 6.
%e A247856 0.313233080986945912630786486472172800439251174505225397...
%t A247856 twinPrimes = Select[{#, #+2}& /@ Prime[Range[100]], PrimeQ[Last[#]]&] // Flatten; u2 = FromContinuedFraction[Join[{0}, twinPrimes]]; RealDigits[u2, 10, 101] // First
%Y A247856 Cf. A077800, A108170, A127552.
%K A247856 nonn,cons
%O A247856 0,1
%A A247856 _Jean-François Alcover_, Sep 25 2014