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 A069141 #12 Aug 03 2024 07:09:32 %S A069141 2,6,24,30,720,140,40320,5670,403200,399168,479001600,300300, %T A069141 87178291200,6671808000,92990177280,86837751000,6402373705728000, %U A069141 1158789632000,2432902008176640000,319318388573184,2548754484756480000,53413257724968960000,620448401733239439360000 %N A069141 a(n) = n^2*(n+1)!/(n^tau(n)) where tau(n) is the number of divisors of n. %C A069141 The expression n^2*(n+1)!/(n^tau(n)) is always an integer. n^tau(n) is also the product of square divisors of n (cf. A062758). %H A069141 Amiram Eldar, <a href="/A069141/b069141.txt">Table of n, a(n) for n = 1..448</a> %t A069141 a[n_] := (n+1)! / n^(DivisorSigma[0,n] - 2); Array[a, 23] (* _Amiram Eldar_, Aug 03 2024 *) %o A069141 (PARI) a(n) = (n+1)! / n^(numdiv(n)-2); \\ _Amiram Eldar_, Aug 03 2024 %Y A069141 Cf. A000005, A062758. %K A069141 easy,nonn %O A069141 1,1 %A A069141 _Benoit Cloitre_, Apr 08 2002 %E A069141 a(22)-a(23) from _Amiram Eldar_, Aug 03 2024