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 A084116 #21 Feb 16 2025 08:32:49 %S A084116 2,3,5,6,7,8,10,11,13,14,15,17,19,21,22,23,26,27,29,31,33,34,35,37,38, %T A084116 39,41,43,46,47,51,53,55,57,58,59,61,62,65,67,69,71,73,74,77,79,82,83, %U A084116 85,86,87,89,91,93,94,95,97,101,103,106,107,109,111,113,115,118,119 %N A084116 Numbers m such that A084115(m) = 1. %C A084116 A084113(a(n)) = A084114(a(n)) + 1. %C A084116 Union of primes and multiplicatively perfect numbers (A000040, A007422). %C A084116 A084115(a(n)) = 1; A066729(a(n)) = a(n). %H A084116 Reinhard Zumkeller, <a href="/A084116/b084116.txt">Table of n, a(n) for n = 1..10000</a> %H A084116 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativePerfectNumber.html">Multiplicative Perfect Number</a>. %F A084116 It appears that a(n) = n such that A000005(n)^A000005(n)+1 is prime. - _Carl Najafi_, Oct 19 2011 %t A084116 Select[Range[2, 200], PrimeQ[DivisorSigma[0, #]^DivisorSigma[0, #] + 1] &] (* _Carl Najafi_, Oct 19 2011 *) %o A084116 (Haskell) %o A084116 a084116 n = a084116_list !! (n-1) %o A084116 a084116_list = filter ((== 1) . a084115) [1..] %o A084116 -- _Reinhard Zumkeller_, Jul 31 2014 %o A084116 (PARI) is(n)=isprime(n) || numdiv(n) == 4 \\ _Charles R Greathouse IV_, Oct 19 2015 %Y A084116 Cf. A084110, A066729, A084113, A084114, A084115, A066423 (complement). %K A084116 nonn %O A084116 1,1 %A A084116 _Reinhard Zumkeller_, May 12 2003 %E A084116 Corrected and edited by _Carl Najafi_, Oct 19 2011 %E A084116 Revised by _Reinhard Zumkeller_, Jul 31 2014