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 A272590 #12 May 18 2018 13:06:31 %S A272590 2,8,24,120,840,9240,120120,2042040,38798760,892371480,25878772920, %T A272590 802241960520,29682952539240,1217001054108840,52331045326680120, %U A272590 2459559130353965640,130356633908760178920,7691041400616850556280,469153525437627883933080,31433286204321068223516360 %N A272590 a(n) is the smallest number m such that the multiplicative group modulo m is the direct product of n cyclic groups. %C A272590 Arguably a(1)=3, as the multiplicative group mod 2 has only one element, hence its factorization is the empty product. - _Joerg Arndt_, May 18 2018 %C A272590 For n >= 2, positions of records of A046072. - _Joerg Arndt_, May 18 2018 %F A272590 a(1) = 2, a(n) = 4 * prod(k=1..n-1, prime(k) ) for n >= 2. %F A272590 a(n) = A102476(n) for n >= 2. %F A272590 A002322(a(n)) = A058254(n). %o A272590 (PARI) a(n)=if(n==1,2,4*prod(k=1,n-1,prime(k))); %Y A272590 Cf. A002322, A102476, A058254. %Y A272590 Numbers n such that the multiplicative group modulo n is the direct product of k cyclic groups: A033948 (k=1), A272593 (k=2), A272593 (k=3), A272594 (k=4), A272595 (k=5), A272596 (k=6), A272597 (k=7), A272598 (k=8), A272599 (k=9). %K A272590 nonn %O A272590 1,1 %A A272590 _Joerg Arndt_, May 05 2016