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 A154524 #20 Jul 04 2025 12:37:37 %S A154524 3,5,7,19,23,29,47,61,97,181,233,307,401,887,1021,1087,1361,1481,2053, %T A154524 2293,5407,5857,11059,14281,27277,27803,36497,44987,53017 %N A154524 Primes p such that lcm(1,2,3,...,p-2,p-1,p) - 1 is prime. %C A154524 a(28) > 42000. - _Daniel Suteu_, Oct 06 2018 %C A154524 a(30) > 100000. - _Michael S. Branicky_, Jul 04 2025 %F A154524 A057825 INTERSECT A000040. - _R. J. Mathar_, Jan 14 2009 %e A154524 7 is in the sequence because it is prime and also lcm(1,2,3,4,5,6,7)-1 = 420-1 = 419 is prime. - _Emeric Deutsch_, Jan 16 2009 %p A154524 P := proc(n) options operator, arrow: ilcm(seq(j, j = 1 .. n)) end proc: a := proc(n) if isprime(n) and isprime(P(n)-1) then n else end if end proc: seq(a(n), n = 1 .. 3000); # _Emeric Deutsch_, Jan 16 2009 %Y A154524 Cf. A056604, A154525, A154526. %K A154524 nonn %O A154524 1,1 %A A154524 _Lekraj Beedassy_, Jan 11 2009 %E A154524 a(8)-a(17) from _Ray Chandler_, Jan 16 2009 %E A154524 a(18)-a(22) from _Emeric Deutsch_, Jan 16 2009 %E A154524 a(23)-a(27) from _Daniel Suteu_, Oct 06 2018 %E A154524 a(28)-a(29) from _Michael S. Branicky_, Jul 03 2025