|
%I #10 Feb 21 2019 23:20:31
%S 1,2,3,8,5,36,7,32,27,100,11,144,13,196,225,128,17,324,19,400,441,484,
%T 23,576,125,676,243,784,29,900,31,512,1089,1156,1225,1296,37,1444,
%U 1521,1600,41,1764,43,1936,2025,2116,47,2304,343,2500,2601,2704,53,2916,3025,3136,3249,3364,59,3600
%N A140579^(-1) * A000290, the squares starting (1, 4, 9, ...).
%C For n > 1, a(n) = n iff n is prime.
%C a(n) is n times the least common multiple of the proper divisors of n, a(n) = n*A048671(n). - _Peter Luschny_, Jun 22 2011
%F A140579^(-1) * (1, 4, 9, 16, 25, ...).
%e A140579 = an infinite lower triangular matrix with A014963 in the main diagonal and the rest zeros; where A014963 = (1, 2, 3, 2, 5, 1, 7, ...).
%e a(5) = 5 = (1/A014963(5)) * 25 = (1/5)*25.
%p A140651 := n -> n*ilcm(op(numtheory[divisors](n) minus {1,n})); seq(A140651(i),i=1..60); # _Peter Luschny_, Jun 22 2011
%Y Cf. A140579, A014963.
%K nonn
%O 1,2
%A _Gary W. Adamson_ and _Mats Granvik_, May 20 2008
%E a(15)-a(60) from _Peter Luschny_, Jun 22 2011
|
