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 A227853 #26 Feb 07 2022 21:49:16
%S A227853 5,9,10,20,24,39,49,50,58,67,79,88,91,97,98,103,116,117,134,136,137,
%T A227853 143,148,149,180,181,182,193,201,213,230,234,239,247,253,261,265,267,
%U A227853 275,284,285,286,288,296,301,304,313,321,325,339,347
%N A227853 Numbers k such that 4620*k - 1 is a safe prime (A005385).
%C A227853 The given expression seems to produce safe primes quite frequently. The numbers 6*(4620*a(n)-1) form a subsequence of A230032.
%C A227853 Note that 4620 = 2^2*3*5*7*11.
%C A227853 Is a(4135..4139) = 59497..59501 the only set of 5 terms with common difference = 1? Checked for all terms up to 10^7. - _Zak Seidov_, Nov 02 2013
%C A227853 This is common because 4620 = 12*5*7*11 contains several small prime factors, which reduces the possible 12x-1 remainders, forcing all safe primes to be in other 12x-1 remainders mod 4620. Something similar would happen if 4620 were replaced with 12*5*7*13 = 5460. - _Mark Andreas_, Dec 31 2021
%H A227853 Jon E. Schoenfield, <a href="/A227853/b227853.txt">Table of n, a(n) for n = 1..10000</a>
%o A227853 (PARI) {f=4*3*5*7*11; for(k=1,2000,isprime(p=k*f-1)&&isprime(p\2)&&print1(k","))}
%Y A227853 Cf. A005385, A230032.
%K A227853 nonn
%O A227853 1,1
%A A227853 _M. F. Hasler_, Oct 31 2013