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 A276673 #105 May 26 2024 16:04:17 %S A276673 1,2,3,4,8,19,23,25,28,65,171,183,187,295,351,471,561,634,710,1726, %T A276673 3947,4247,6009,11065,13567,94493,147871,182291 %N A276673 Numbers k such that 94*10^k - 3 is prime. %C A276673 For k > 0, numbers k such that the digits 93 followed by k-1 occurrences of the digit 9 followed by the digit 7 is prime (see Example section). %C A276673 a(29) > 2*10^5. %H A276673 Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of near-repdigit-related numbers</a>. %H A276673 Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/prime_difficulty.txt">Search for 939w7</a>. %e A276673 3 is in this sequence because 94*10^n - 3 = 93997 is prime. %e A276673 Initial terms and associated primes: %e A276673 a(1) = 1, 937; %e A276673 a(2) = 2, 9397; %e A276673 a(3) = 3, 93997; %e A276673 a(4) = 4, 939997; %e A276673 a(5) = 8, 9399999997, etc. %t A276673 Select[Range[0, 100000], PrimeQ[94*10^# - 3] &] %o A276673 (PARI) is(n)=ispseudoprime(94*10^n - 3) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A276673 Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. %K A276673 nonn,more %O A276673 1,2 %A A276673 _Robert Price_, Nov 16 2016 %E A276673 a(27)-a(28) from _Robert Price_, May 03 2020