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 A294396 #48 Jan 31 2023 08:35:36 %S A294396 0,2,38,80,9230,25598,39500 %N A294396 Numbers k such that 12*10^k + 1 is prime. %C A294396 k must be even since 12*10^k + 1 is divisible by 11 if k is odd. - _Robert G. Wilson v_, Feb 12 2018 %C A294396 a(7) > 27440. - _Robert G. Wilson v_, Feb 17 2018 %C A294396 a(8) > 10^5. - _Jeppe Stig Nielsen_, Jan 31 2023 %e A294396 13 and 1201 are prime, so 0 and 2 are the initial values. %t A294396 ParallelMap[ If[ PrimeQ[12*10^# +1], #, Nothing] &, 2 + 6Range@ 4500] (* _Robert G. Wilson v_, Feb 13 2018 *) %o A294396 (PARI) isok(k) = isprime(12*10^k + 1); \\ _Altug Alkan_, Mar 04 2018 %Y A294396 Cf. A001562, A096507, A056797, A056807, A056806, A102940, A056805, A056804, A096508, A102975, A289051, A099017, A295325, A273002, A102945, A282456, A267420. %Y A294396 Cf. A062339 (primes with digit sum 4). %K A294396 nonn,more %O A294396 1,2 %A A294396 _Patrick A. Thomas_, Feb 12 2018 %E A294396 a(5) from _Robert G. Wilson v_, Feb 12 2018 %E A294396 a(6) from _Robert G. Wilson v_, Feb 13 2018 %E A294396 a(7) from _Jeppe Stig Nielsen_, Jan 28 2023