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 A046882 Ultrafactorials: a(n) = n!^n!. 10
 1, 1, 4, 46656, 1333735776850284124449081472843776 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(5) = 3175 042373 780336 892901 667920 556557 182493 442088 021222 004926 225128 381629 943118 937129 098831 435345 716937 405655 305190 657814 877412 786176 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000. - Jonathan Vos Post, Dec 09 2004 Note that, by analogy with factorial primes, subfactorial primes, superfactorial primes and hyperfactorial primes, if a(n)+1 or a(n)-1 is prime, it should be called an ultrafactorial prime. These begin: a(0)+1 = a(1)+1 = 2, a(2)-1 = 3, a(2)+1 = 5. Are there any more? Note that a(3) = 46657 = 13 * 37 * 97 is a 3-brilliant number. a(3)-5, a(3)-3 and a(3)+5 are semiprime; a(3)-7 and a(3)+7 are primes. - Jonathan Vos Post, Dec 09 2004 LINKS Eric Weisstein's World of Mathematics, Ultrafactorial. FORMULA Sum_{n>=1} 1/a(n) = A100085. - Amiram Eldar, Nov 11 2020 MATHEMATICA lst={}; Do[a=n!^n!; AppendTo[lst, a], {n, 6}]; lst (* Vladimir Joseph Stephan Orlovsky, Oct 01 2008 *) CROSSREFS Cf. A002109, A100085. Cf. A000166, A000178, A002982. Sequence in context: A173138 A275587 A132638 * A165812 A218405 A259492 Adjacent sequences: A046879 A046880 A046881 * A046883 A046884 A046885 KEYWORD nonn AUTHOR Camillo Lamonaca (Camillo.Lamonaca(AT)dva.gov.au) STATUS approved

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Last modified March 22 18:49 EDT 2023. Contains 361433 sequences. (Running on oeis4.)