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 A137811 #21 Jul 19 2025 10:12:25
%S A137811 1,2,3,11,25,27,37,40,78,112,119,142,157,229,251,1603,2339,2874,3731,
%T A137811 4768,5690,6920,6930,29725,43058,45468,200815,359799,382007,441847,
%U A137811 606279,712818,1129757,5122515
%N A137811 Number of digits in the n-th Woodall prime.
%C A137811 Woodall primes are prime numbers of the form k*2^k-1.
%H A137811 Allan Cunningham and H. J. Woodall, <a href="https://archive.org/details/messengerofmathe47cambuoft/page/n9/mode/2up">Factorisation of Q=(2^q+-q) and (q 2^q+-1)</a>, Messenger Math., Vol. 47 (1917), pp. 1-38.
%H A137811 Wilfrid Keller, <a href="https://doi.org/10.1090/S0025-5718-1995-1308456-3">New Cullen Primes</a>, Mathematics of Computation, Vol. 64, No. 212 (Ocober 1995), pp. 1733-1741.
%H A137811 Woodhall Primes, <a href="http://web.archive.org/web/20161028080439/http://www.prothsearch.net/woodall.html">Definition And Status</a>.
%F A137811 a(n) = A055642(A050918(n)).
%e A137811 As the sixth Woodall prime is a 27-digit number, we have a(6)= 27
%t A137811 IntegerLength/@Select[Table[n 2^n-1,{n,10000}],PrimeQ] (* The program generates the first 18 terms of the sequence. *) (* _Harvey P. Dale_, Feb 05 2023 *)
%Y A137811 Cf. A055642, A050918, A137716, A002234.
%K A137811 nonn,base,hard,more
%O A137811 1,2
%A A137811 _Ant King_, Feb 12 2008
%E A137811 a(28)-a(34) from _Amiram Eldar_, Jul 19 2025