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 A080840 #30 Feb 16 2025 08:32:48
%S A080840 1,8,41,203,1216,8144,58622,440258,3424680,27409999,224373161,
%T A080840 1870585459,15834656003,135779962760,1177207270204
%N A080840 Number of cousin primes < 10^n.
%C A080840 The corresponding numbers for twin primes and sexy primes are in A007508 and A080841, the greater of twin primes, cousin primes and sexy primes are in A006512, A046132 and A046117 respectively.
%C A080840 In this sequence, only the upper member of each prime cousin pair is counted. See A152052 for the variant where only the lower member is counted. - _James Rayman_, Jan 17 2021
%H A080840 A. Granville and G. Martin, <a href="http://www.dms.umontreal.ca/~andrew/PDF/PrimeRace.pdf">Prime number races</a>, Amer. Math. Monthly vol 113, no 1 (2006) p 1.
%H A080840 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CousinPrimes.html">Cousin Primes</a>.
%o A080840 (PARI) {c=0; p=5; for(n=1,9, while(p<10^n,if(isprime(p-4),c++); p=nextprime(p+1)); print1(c,","))}
%Y A080840 Cf. A007508, A080841, A006512, A046132, A046117, A152052, A152127.
%K A080840 nonn,hard,more
%O A080840 1,2
%A A080840 _Jason Earls_, Mar 28 2003
%E A080840 a(8) and a(9) from _Klaus Brockhaus_, Mar 30 2003
%E A080840 More terms from _R. J. Mathar_, Aug 05 2007
%E A080840 a(13)-a(15) from _Martin Ehrenstein_, Sep 03 2021