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 A049433 #24 Jun 14 2025 07:13:58 %S A049433 3,4,6,8,9,12,28,78,99,184,286,291,398,411,600,718,732,889,1963,2240, %T A049433 2242,2533,8800,11403,18335,20277,21029 %N A049433 Numbers k such that k! - (k-1)! - 1 is prime. %C A049433 There is no further term up to 1400. - _Farideh Firoozbakht_, Jul 18 2003 %C A049433 a(25) > 12000. [_Donovan Johnson_, Dec 18 2009] %H A049433 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a> %F A049433 a(n) = A090704(n) + 1 = n*n! + 1 = ((n+1)-1)*n! + 1 = (n+1)! - n! + 1 . %e A049433 6 is a term since 6! - (6-1)! - 1 = 599 is prime. %Y A049433 Cf. A049432, A049985, A090704. %Y A049433 Cf. A001272, A002981, A002982. %K A049433 nonn %O A049433 1,1 %A A049433 Paul Jobling (paul.jobling(AT)whitecross.com) %E A049433 More terms from _Farideh Firoozbakht_, Jul 18 2003 %E A049433 Corrected offset, edited definition and a(19)-a(24) from _Donovan Johnson_, Dec 18 2009 %E A049433 a(25)-a(27) from _Michael S. Branicky_, Jun 13 2025