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 A204578 #9 Oct 18 2021 13:21:36 %S A204578 3,23,6103515623,1490116119384765623, %T A204578 88817841970012523233890533447265623, %U A204578 11754943508222875079687365372222456778186655567720875215087517062784172594547271728515623,44841550858394146269559346665277316200968382140048504696226185084473314645947539247572422027587890623 %N A204578 Primes of the form 5^k-2. %C A204578 See the sequence A109080 for the corresponding exponents k. %C A204578 The number a(3) = 6103515623 is also in A095304, A104090 and A128472. %F A204578 a(n) = 5^A109080(n)-2. %o A204578 (PARI) for(i=0,999, ispseudoprime(t=5^i-2) & print1(t",")) %Y A204578 Cf. A109080. %K A204578 nonn,less %O A204578 1,1 %A A204578 _M. F. Hasler_, Jan 30 2012